Given at the end is an article. Analyze it and output in the following JSON format.
{
"analysis": {
"bias": {
"score": "1-10, where 1-10 measures UNFAIR or UNHELPFUL bias.
As the AI analyst, you must judge:
1. Fairness of Bias:
- Is the tone/alarm proportional to events?
- Is criticism warranted by facts?
- Are similar actions judged equally?
2. Utility of Bias:
- Does the bias help readers understand real implications?
- Does it highlight genuine concerns that neutral language might minimize?
- Does it provide valuable context through its perspective?
Example: An article about climate change might use emotional language
and scary scenarios. While this is technically 'bias', it might be
USEFUL bias if it helps readers grasp real dangers that cold, neutral
language would understate.
A high bias score should only be given when bias is both unfair AND unhelpful.",
"description": "Explain both unfair and useful bias found. For each biased element:
1. Is it fair/warranted?
2. Does it serve a valuable purpose for readers?
3. Should it be removed or retained?"
},
"missing_context_misinformation": {
"score": "1-10",
"points": [
"", # DIRECTLY provide essential context the reader needs without ANY phrases like "the article lacks/doesn't/fails to mention/omits" etc. Simply state the relevant facts. Each point up to 5 sentences as needed. Up to 10 points. NEVER refer to the article itself or what it's missing - just supply the information directly. The missing context should try to compensate for the bias in the article, and not just add related information.
]
},
"disinformation_lies": {
"score": "1-10",
"points": [
"" # Provide corrections for verifiably false statement. These lines should be brief. Upto 10 points.
# Use Wikipedia (via the search tool) to verify events and dates up through 2025-07-07. Any event dated ≤ 2025-07-07 should not be marked as disinformation if it matches Wikipedia. Only flag statements you can not verify or that Wikipedia contradicts as of 2025-07-07.”
]
}
},
"summary": [], # A list of 2 to 5 paragraphs. Provide a version that: * Retains key facts and proportional concerns, * Removes unfair bias while keeping warranted criticism, * Adds critical missing context, * Corrects any inaccuracies. Remove author attribution. Maintain article's POV - no meta-references. You can decide the most appropriate length based on the article.summary can be longer than the article if needed.
"title": "Provide an Appropriate Title Based on the Article's Content.",
"changes_made": [
"List significant changes made in the summary",
"Include both removals and additions",
"Note bias adjustments"
],
"key_words": [
"3-10 relevant terms to help identify related articles",
"Focus on major themes and topics"
],
"keywords_update": {
"keyword-to-add-or-update": "new summary or updated to replace the previous"
}
}
KEYWORDS UPDATE INSTRUCTIONS:
- We want to save new information from beyond your knowledge cutoff of Mar 2024.
- Information can come from the provided article or Wikipedia.
- Pick up to 3 keywords of highest importance to update with new information.
- If a keyword lacks a summary, write one from scratch.
- For each keyword, list one line per new fact (up to 50 sentences per keyword).
- Each fact must:
1. Be one or two sentences long.
2. End with 1-3 references in brackets, e.g. [apnews], [nytimes,wikipedia].
3. Immediately after the reference(s), append a hyphen and the date of the event or when the fact was reported, in ISO format:
`Statement. [source] - [YYYY-MM-DD]`
- If you update an existing keyword's source (e.g. [foxnews] → [apnews]), ensure the replacement is supported by an article.
- Ensure each keyword is specific enough that its new facts warrant inclusion.
<example>
ARTICLE TOPIC
Raiding of 100+ immigrants allegedly illegal alients and alleged members from the Venezuelan gang Tren de Aragua, MS-13, and the Hells Angels for deportation. Authorities also found drugs at the underground nightclub at a strip mall in Colorado Springs. President Donald Trump praised the raid, saying on TruthSocial it had targeted some of the worst people in the US, whom he alleged judges are reluctant to deport.
keywords worth updating:
tren-de-aragua (I am sure this gang has a big list of information, but this deportation will be worth a mention)
tren-de-aragua+deportation (a more specific keyword that can take more detail about this incident)
trump+illegal_deportation (add this to the list of illegal deportations conducted by trump administration)
colorado_springs (this is a unique event for this town. an update here will add some trivia.)
trump+immigration (a key fact worth mentioning about how trump is implementation his immigration policies)
keywords to not update:
trump (too broad. not one of top 50 facts related to trump.)
illegal_deportation (depending upon existing content, may be too crowded for this incident to be added)
colorado (too broad, unlikely to fit this event in top 50)
drug_raids (too broad, unlikely to fit this event in top 50)
</example>
<existing_keywords_summaries>
atlantic-hurricane-season-2025 : The 2025 Atlantic hurricane season began on June 1 and will end on November 30, with Tropical Storm Andrea becoming the first named storm on January 21. [wikipedia] - 2025-01-21
The season started relatively slowly compared to the average first named storm formation date of around June 20. [wikipedia] - 2025-01-21
NOAA's seasonal outlook forecasts up to 10 hurricanes for 2025 compared to the average of 7, with 3-5 expected to reach major hurricane status (Category 3 or stronger). [wikipedia] - 2025-01-21
Despite the slower start, the 2025 season is still expected to be above-average, particularly following the exceptionally destructive 2024 season. [wikipedia] - 2025-01-21
kerr-county+flood-warning-system : Kerr County, Texas does not have a warning system specifically for flooding, according to county officials following the July 2025 Guadalupe River flash flood disaster. [article] - 2025-07-04. County Judge Rob Kelly stated that officials had no reason to believe the July 3-4, 2025 flooding would be anything like what occurred, despite regular flooding in the area. [article] - 2025-07-04. Kerrville City manager said they could not anticipate the severity of the flooding despite National Weather Service warnings because the event happened so quickly. [article] - 2025-07-04.
texas-flash-floods-2025 : Flash floods along the Guadalupe River killed at least 30 people including nine children, with waters rising 26 feet on Friday. [article] - 2025-01-10
Twenty-seven girls remain missing from Camp Mystic, a Christian camp in Hunt, Texas, following the deadly flooding. [article] - 2025-01-11
Rescue workers saved at least 850 people in 36 hours, with Texas Governor Greg Abbott reporting people found 'clinging to trees to save their lives.' [article] - 2025-01-11
President Trump called the deaths 'shocking' and announced Homeland Security Secretary Kristi Noem would visit the disaster area. [article] - 2025-01-11
trump+california-national-guard : The 9th US Circuit Court of Appeals allowed Trump to maintain control over approximately 4,000 California National Guard members federalized during Los Angeles immigration protests in June 2025. [CNN] - 2025-06-12. The appeals court ruled that Trump likely exercised his statutory authority lawfully under 10 USC 12406, rejecting Governor Newsom's arguments that proper procedures weren't followed. [CNN] - 2025-06-12. Defense Secretary Pete Hegseth delivered Trump's June 7 federalization memo to California's top general rather than directly to Governor Newsom, which the court deemed acceptable since the general serves as an 'agent' of the governor. [CNN] - 2025-06-12.
us-embassy-evacuation-procedures : U.S. Ambassador to Israel Mike Huckabee announced via social media that the embassy was working on evacuation flights and cruise ships for American citizens during the Israel-Iran conflict. [cbsnews] - 2025-06-18. American citizens were advised to enroll in the Smart Traveler Enrollment Program (STEP) to receive updates about potential evacuation assistance. [cbsnews] - 2025-06-18. The State Department raised its travel advisory for Israel to Level 4 'do not travel,' the highest warning possible, as evacuation planning continued. [cbsnews] - 2025-06-18.
extreme-heat-wave-2025 : A dangerous heat wave affected the eastern United States in late June 2025, with over 150 million people under heat alerts. [cnn] - 2025-06-24. New York's Central Park reached 96 degrees, matching a record last seen in 1888. [cnn] - 2025-06-24. The National Weather Service issued a rare Level 4-of-4 extreme heat risk through Thursday, stretching from the Midwest to the Northeast. [cnn] - 2025-06-24. Over 250 daily temperature records could be broken during the peak heat, with temperatures 15-20 degrees above normal. [cnn] - 2025-06-24. Major cities experienced potentially historic temperatures, with New York City reaching near 100 degrees for the first time in June since 1966. [cnn] - 2025-06-24.
new-york-city+temperature-records : New York City's Central Park reached 96 degrees on June 23, 2025, tying the daily record last seen in 1888. [cnn] - 2025-06-24. Tuesday's forecast high could reach 100 degrees, which would be the first time NYC hit that temperature in June since 1966. [cnn] - 2025-06-24. The last time New York City reached 100 degrees was on July 18, 2012. [cnn] - 2025-06-24. The June 2025 heat wave marked the hottest day the city had experienced since August 2022. [cnn] - 2025-06-24.
heat-related-illness+emergency-response : During the June 2025 heat wave, 16 people were hospitalized after graduations in Paterson, New Jersey, with over 150 people evaluated for heat-related illnesses. [cnn] - 2025-06-24. All 16 hospitalized individuals were reported in stable condition at the time of transport. [cnn] - 2025-06-24. The Washington Monument was closed Monday and Tuesday due to an Extreme Heat Warning during the heat wave. [cnn] - 2025-06-24. Heat remains the deadliest form of extreme weather in the US, with risks particularly severe for children, elderly, and those with pre-existing conditions. [cnn] - 2025-06-24.
guadalupe-river+flash-flooding : A devastating flash flood struck the Guadalupe River in Texas Hill Country on July 3-4, 2025, when four months' worth of rain fell in just hours as thunderstorms stalled over the area. [article] - 2025-07-04. The flooding produced a 20-foot flood wave that moved down the river around 5 a.m., triggering the river's second-highest crest on record. [article] - 2025-07-04. Up to 15 inches of rain fell in some locations, far exceeding the initially forecast 5-7 inches. [article] - 2025-07-04. The flood swept away homes, vehicles, and structures including summer camps along the river. [article] - 2025-07-04.
america250+celebrations : Trump announced that the UFC fight would be one of many special events planned for America's 250th independence anniversary on July 4, 2025. [article] - 2025-01-19. He stated that 'every one of our national parks, battlefields and historic sites are going to have special events in honour of America250.' [article] - 2025-01-19.
texas-flash-floods-2025 : Flash floods along the Guadalupe River killed at least 30 people including nine children, with waters rising 26 feet on Friday. [article] - 2025-01-10
Twenty-seven girls remain missing from Camp Mystic, a Christian camp in Hunt, Texas, following the deadly flooding. [article] - 2025-01-11
Rescue workers saved at least 850 people in 36 hours, with Texas Governor Greg Abbott reporting people found 'clinging to trees to save their lives.' [article] - 2025-01-11
President Trump called the deaths 'shocking' and announced Homeland Security Secretary Kristi Noem would visit the disaster area. [article] - 2025-01-11
camp-mystic-disaster :
guadalupe-river-flooding :
kerr-county-flood-2025 :
trump-disaster-declaration :
texas-flash-floods-2025 : Flash floods along the Guadalupe River killed at least 30 people including nine children, with waters rising 26 feet on Friday. [article] - 2025-01-10
Twenty-seven girls remain missing from Camp Mystic, a Christian camp in Hunt, Texas, following the deadly flooding. [article] - 2025-01-11
Rescue workers saved at least 850 people in 36 hours, with Texas Governor Greg Abbott reporting people found 'clinging to trees to save their lives.' [article] - 2025-01-11
President Trump called the deaths 'shocking' and announced Homeland Security Secretary Kristi Noem would visit the disaster area. [article] - 2025-01-11
camp-mystic-disaster :
guadalupe-river-flooding :
kerr-county-flood-2025 :
trump-disaster-declaration :
</existing_keywords_summaries>
<wikipedia_requested_titles>
TITLE Thunderstorm
Thunderstorms are small, intense weather systems that make strong winds, heavy rain, lightning, and thunder. Thunderstorms can happen anywhere with two conditions: the air near the Earth's surface must be warm and moist (with lots of liquid), and the atmosphere must be unstable. 100 lightning bolts hit the earth every second, and at any one moment, about 1,800 thunderstorms happen around the earth.
Thunderstorms are rare in winter, mostly because of cold weather. When they happen, it is called thundersnow. Thundersnow is common in blizzards.
== Cycle ==
Usually there are more clouds in the afternoon than in early morning. This is because the Sun has warmed the ground, and the ground has warmed the air. Warm air rises (updrafts) and blows upward from the ground. When the air has gone high enough, the water vapor in it condenses into a cloud. The height where this happens depends on the temperature and humidity of the air. Sometimes the air can rise up as high as 5,000 to 10,000 feet (1,500 to 3,000 m) before a small cumulus cloud can condense from the invisible water vapor.
High, puffy little clouds do not change until a lot of moisture is added. This moisture helps the updraft. Moisture can add heat, which means the cloud will warm up inside and go up even faster. The moisture makes the cumulus cloud "mushroom" upwards and turn into a tall cumulus cloud. The winds inside this cloud are very strong. Thunder and lightning begins when the top of the cloud is 25,000 feet (7,280 m) high. The inside of the cloud is, by this time, cold enough so that the water drops are turned into ice crystals. A cumulus cloud stops growing when it hits the warm stratosphere. Some thunderstorms grow twice as high as Mount Everest.
Strong upper winds in the stratosphere smooth and spread the top of the cloud. This makes the cloud look like the top of a mushroom or an anvil. The ice crystals in the anvil cloud give it a fuzzy look. As a thunderstorm grows, water drops or ice crystals inside the cloud hit and mix with each other, getting bigger. The bottom of the cloud grows dark, with water about to fall. When the drops become so heavy that the winds inside the cloud cannot keep them up any more, they fall from the cloud as rain or hail. Even as they fall, the water drops grow by absorbing the smaller drops and make big raindrops. Hail becomes bigger inside the cloud. One thunderstorm cloud usually runs out of energy in about 30 to 50 minutes. But supercell thunderstorms can last for hours until they dissipate by outflow.
== Lightning ==
Thunderstorms are very active with electricity and so are also called electrical storms. Lightning is a large electrical discharge that happens between two opposite charged surfaces.
When lightning strikes, energy is let out. This energy moves to the air and makes air spread quickly and send out sound waves. Thunder is the sound that comes from the rapid spread of air along the lightning strike. Thunder is slower than lightning, because light is faster than sound.
== Severe thunderstorms ==
Only about 10% of thunderstorms are thought to be severe. Severe thunderstorms cause high winds of more than 58 miles per hour (93 km/h), hail 1 inch in diameter (24 mm), flash floods, and tornadoes. Hailstorms damage crops, damage the metal on cars, and break windows. Sudden flash floods that happen because of heavy rains is the biggest reason for weather-related deaths.
Lightning, which happens with all thunderstorms, starts thousands of forest fires each year in the United States. Lightning also kills or injures hundreds of people a year in the United States.
Regular thunderstorms begin when warm air near the ground mix with moist air, which makes an updraft (a wind that goes upward). A severe thunderstorm needs a strong updraft and a strong downdraft. A strong updraft is made when, firstly, the ground is very hot; secondly, when the air is very moist; and thirdly, the air above is very cold. When the updraft gets stronger, so does the thunderstorm.
Flash floods happen when slow-moving thunderstorms pour down much more water than usual in a small area. It rains so hard that the water can not soak into the ground fast enough, and the water rushes down the mountainsides or hills into streams and rivers. These streams and rivers cannot carry all the water, so it quickly floods. The most severe flash floods make the water level rise dangerously in streams, dry places, or canyons. Flash floods can make terrible mud slides and can move very quickly. They can roll big rocks, tear out trees, and destroy buildings and bridges.
Flash floods can also happen when two or more thunderstorms hit the same spot, one right after the other. They can happen when a dam bursts open or ice breaks up. Flash floods can also happen when it rains very hard on quickly melting snow.
== Benefits ==
Thunderstorms do not do only damage; however, they can be a great help to man and all living creatures. We get lots of water for many continents during the summer. Plants receive lots of life-giving rain when they need it. Without the thunderstorms, many continents would become dry. Fish would die, crops would fail, and animals would die.
Thunderstorms are also our natural air conditioners. Hot air at the surface rises up into the high atmosphere where the heat is put out into space. Clouds give us shade, and rain can cool down a hot day. Without thunderstorms, the earth would be as much as 20 °F (11 °C) warmer. In the summer, dust, haze, and other pollutants come together in the lower atmosphere. When the air rises, either in cumulus clouds or in thunderstorms, it spreads the pollution higher up into the atmosphere. Rain from thunderstorms washes away many of these pollutants out of the air.
Lightning in thunderstorms also helps keep the electrical balance between the earth and the atmosphere. Lightning is also fertilizer. When it splits through the sky, it changes nitrogen gas in the air to nitrogen compounds. These fall to the ground and are added to the soil. Nitrogen is one of the main ingredients in fertilizer. Ten percent of the nitrogen fertilizer needed for farming is made by lightning.
So, even though thunderstorms are dangerous, they can be a great help. They give summer water, cool the earth, and clean the air. Lightning balances the earth's electricity and helps fertilize the soil. And after a thunderstorm, sometimes there is a rainbow.
== Keeping safe in a storm ==
Some tips to keep safe in a thunderstorm are:
If lightning comes near, try to find shelter in a house, car, or low place under some small trees, but not in a shed. Inside a house, do not use the telephone or any electrical things. Do not take a bath or a shower.
Stay away from water because water conducts electricity.
Do not stand on a hilltop. Try not to be the tallest object.
Do not look for shelter under a tree by itself.
Stay away from metal (like pipes, fences, and wire clotheslines).
If your hair stands on end while outside, immediately drop to the ground and curl up in a ball-like shape.
If there is a flash flood, stay out of low places. Cars should not be driven through water that is flowing over a road or bridge. It might look shallow (not deep), but quickly flowing water can wash a car right off a road or a bridge. It only takes two feet of water to float most cars. Also, the road under the water might already have been washed out, leaving a deep hole. A flash flood can easily turn over a car and trap everyone inside. So, if your car stops in flood waters, get out as fast as possible and run to higher ground. Nearly half the people who die in flash floods in the United States die inside cars.
== References ==
== Other websites ==
Anatomy of a thunderstorm Archived 2006-02-18 at the Wayback Machine
Electronic Journal of Severe Storms Meteorology
Social & Economic Costs of Thunderstorms & High Winds Archived 2009-01-26 at the Wayback Machine NOAA Economics
Thunderstorm photography in Germany Archived 2007-07-14 at the Wayback Machine
TITLE Global warming
Climate change refers to long-term changes in temperature, precipitation, and other atmospheric conditions on Earth. It primarily involves the warming of the planet due to increased concentrations of greenhouse gases, like carbon dioxide and methane, from human activities such as burning fossil fuels, deforestation, and industrial processes. These changes can lead to a variety of impacts, including more extreme weather events, rising sea levels, and disruptions to ecosystems and agriculture.
When people talk about climate change they are usually talking about the problem of human-caused global warming, which is happening now (see global warming for more details). But the climate of the Earth has changed over not just thousands of years, but tens or hundreds of millions of years.
The earth's climate changes over time, so it could be hotter or colder at a certain time. For example about 60 million years ago there were a lot of volcanoes, which burnt a lot of underground organic matter (squashed and fossilized dead plants and animals became coal, gas and oil). A large amount of carbon dioxide and methane went up in the air.
At times in the past, the temperature was much cooler, with the last glaciation ending about ten thousand years ago. Ice Ages are times when the Earth got colder, and more ice froze at the North and South Poles. There have been times when Earth has been covered in ice, and was much colder than today.
There is no one reason why there are Ice Ages. Changes in the Earth's orbit around the Sun, and the Sun getting brighter or dimmer are events which do happen. Also how much the Earth is tilted compared to the Sun might make a difference. Another source of change is the activities of living things (see Great Oxygenation Event and Huronian glaciation).
== Hot Earth ==
Sometimes, before there were people, the Earth's climate was much hotter than it is today. For example about 60 million years ago there were a lot of volcanoes, which burnt a lot of underground organic matter (squashed and fossilized dead plants and animals like coal, gas and oil) so a lot of carbon dioxide and methane went up in the air like nowadays. This made the Earth hot enough for giant tortoises and alligators to live in the Arctic.
== Cold Earth ==
=== Glaciations ===
At times in the past, the temperature was much cooler, with the last glaciation ending about ten thousand years ago.
=== Ice Ages ===
Ice Ages are long times (much much longer than glaciations) when the Earth got colder, and more ice froze at the North and South Poles. Sometimes even the whole Earth was covered in ice, and was much colder than today. There is no one reason why there are Ice Ages. Changes in the Earth's orbit around the Sun, and the Sun getting brighter or dimmer are events which do happen. Also how much the Earth is tilted compared to the Sun might make a difference. Another source of change is the activities of living things (see Great Oxygenation Event and Huronia glaciation).
== History of climate change studies ==
Joseph Fourier in 1824, Claude Pouillet in 1827 and 1838, Eunice Foote (1819–1888) in 1856, Irish physicist John Tyndall (1820–1893) in 1863 onwards, Svante Arrhenius in 1896, and Guy Stewart Calendar (1898–1964) discovered the importance of carbon dioxide (CO2) in climate change. Foote's work was not appreciated, and not widely known. Tyndall proved there were other greenhouse gases as well. Nils Gustaf Ekholm in 1901 invented the term.
=== The Sun ===
The Sun gets a little bit hotter and colder every 11 years. This is called the 11-year sunspot cycle. The change is so small that scientists can barely measure how it affects the temperature of the Earth. If the Sun was causing the Earth to warm up, it would warm both the surface and high up in the air. But the air in the upper stratosphere is actually getting colder. Therefore the changes in the Sun are not causing the global warming which is happening now.
According to the United Nations’ Intergovernmental Panel on Climate Change (IPCC), the current scientific consensus is that long and short-term variations in solar activity play only a very small role in Earth’s climate. Warming from increased levels of human-produced greenhouse gases is actually many times stronger than any effects due to recent variations in solar activity.
For more than 40 years, satellites have observed the Sun's energy output, which has gone up or down by less than 0.1 percent during that period. Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 270 times greater than the slight extra warming coming from the Sun itself over that same time .[2]
== Sustainable energy and environment ==
Renewable energy or sustainable energy includes any energy source that cannot be exhausted. It can remain viable for a long period of time without running out or lasts forever. Examples are solar, wind, hydropower (water), geothermal, tidal and biomass.
Sustainable energy choices play a crucial role in mitigating the impact of human activities on the environment. Here's an overview of some key sustainable energy options and their environmental impacts according to research:
=== Solar energy ===
Sunlight from the Sun when converted produces solar energy. It is in abundance and freely available. The type of energy obtained is clean and easily renewable. It has low maintenance cost and can generate energy in any climate.
=== Wind energy ===
Another clean form of energy is wind. This energy is a plentiful source of renewable energy source. However, it is only available sometimes.
Through history, the use of wind power has waxed and waned, from the use of windmills in centuries past to high tech wind turbines on wind farms today.
== Related pages ==
Ecology
Intergovernmental Panel on Climate Change
Palaeoclimatology
== References. ==
TITLE List of common misconceptions
This is a list of popular wrong ideas and beliefs about notable topics. Each has been discussed in published literature.
== History ==
=== Ancient to early modern history ===
There is no evidence that Vikings wore horns on their helmets.
King Canute did not command the tide to reverse in a fit of delusional arrogance.
Christopher Columbus's efforts to obtain support for his voyages were not hampered by a European belief in a flat Earth. Sailors and navigators of the time knew that the Earth was like a sphere, but (correctly) disagreed with Columbus's estimate of the distance to India, which was approximately one-sixth of the actual distance. The intellectual class had known that the Earth was spherical since the works of the Greek philosophers Plato and Aristotle. Eratosthenes made a very good estimate of the Earth's diameter around 240 BC.
There is a legend that Marco Polo imported pasta from China which originated with the Macaroni Journal, published by an association of food industries. Durum wheat, and thus pasta as it is known today, was introduced by Arabs from Libya, during their conquest of Sicily in the late 7th century.
Contrary to the popular image of the Pilgrim Fathers, the early settlers of the Plymouth Colony in present-day Plymouth, Massachusetts did not dress in black, wear buckles, or wear black steeple hats. According to historian James W. Baker, this image was formed in the 19th century when buckles were a kind of emblem of quaintness.
Marie Antoinette did not actually use the words "let them eat cake" when she heard that the French peasantry was starving because they did not have bread to eat. The phrase was first published in Rousseau's Confessions when Marie was only 10 years old. Marie Antoinette was unpopular, and many attributed the phrase "let them eat cake" to her, in keeping with her reputation as being hard-hearted and disconnected from her subjects.
George Washington did not have wooden teeth. According to a study of Washington's four known dentures by a forensic anthropologist, the dentures were made of gold, hippopotamus ivory, lead, and human and animal teeth (including horse and donkey teeth).
The United States Declaration of Independence was not signed on July 4, 1776. The final language of the document was approved by the Second Continental Congress on that date, it was printed and distributed on July 4 and 5, but the actual signing occurred on August 2, 1776.
The United States Constitution was written on parchment, not hemp paper.
=== Modern history ===
Napoleon I (Napoleon Bonaparte) (pictured) was not as short as people thought. After his death in 1821, his height was found to be 5 feet 2 inches in French feet. This is the same as 5 feet 6.5 inches in modern English feet, or 1.686 metres.
According to Time magazine, there is a common misconception among Americans that Abraham Lincoln freed all the millions of American slaves with the Emancipation Proclamation of January 1863, but the Confederate constitution had prohibited other nations from freeing slaves in Rebel states. The Thirteenth Amendment, ratified on December 6, 1865, officially abolished (except as a punishment for crime) in all of the United States, under President Andrew Johnson, 8 months after Lincoln had died.
Italian dictator Benito Mussolini did not "make the trains run on time". Much of the repair work had been performed before Mussolini and the Fascists came to power in 1922. Accounts from the era also suggest that the Italian railways' legendary adherence to timetables was more myth than reality.
During the German Invasion of Poland in 1939, there is no evidence of Polish Cavalry mounting a brave but futile charge against German tanks using lances and sabres. Polish cavalry still carried the sabre, but were trained to fight as highly mobile, dismounted infantry and issued with light anti-tank weapons.
During World War II, King Christian X of Denmark did not thwart Nazi attempts to identify Jews by wearing a yellow star himself. Jews in Denmark were never forced to wear the Star of David. The Danes did help most Jews flee the country before the end of the war.
Albert Einstein did not fail mathematics in school. When shown a column claiming this fact, Einstein said "I never failed in mathematics... before I was fifteen I had mastered differential and integral calculus".
John F. Kennedy's words "Ich bin ein Berliner" are standard German for "I am a Berliner". An urban legend has it that due to his use of the indefinite article ein, Berliner is translated as jelly doughnut, and that the population of Berlin was amused by the supposed mistake. The word Berliner is not commonly used in Berlin to refer to the Berliner Pfannkuchen; they are usually called ein Pfannkuchen.
Eva Perón never uttered the quote "I will return and I will be millions". The quote was first formulated by the indigenous leader Túpac Katari in 1781 shortly before being executed. The misattribution to Eva Perón originates from a poem by José María Castiñeira de Dios written in Eva Perón's first-person narrative nearly ten years after her death. There is a similar quote in the Spartacus movie.
== Legislation and crime ==
A common misconception is that you must wait at least 24 hours before filing a missing person's report. This is rarely the case. In many cases if there is evidence of violence or of an unusual absence, law enforcement agencies sat to begin an investigation soon after they are missing.
Entrapment law in the United States does not require police officers to identify themselves as police in the case of a sting or other undercover work. The law is specifically about leading people to commit crimes they would not have considered in the normal course of events.
== Food and cooking ==
Searing meat does not "seal in" moisture, and in fact may actually cause meat to lose moisture. Generally, the value in searing meat is that it creates a brown crust with a rich flavor.
Some cooks believe that food items cooked with wine or liquor will be non-alcoholic, because alcohol's low boiling point causes it to evaporate quickly when heated. However, a study found that some of the alcohol remains: 25% after 1 hour of baking or simmering, and 10% after 2 hours.
Sushi does not mean "raw fish", and not all sushi includes raw fish. The name sushi refers to the vinegared rice used in it. Sushi is made with sumeshi, rice which has been gently folded with rice vinegar, salt, and sugar dressing. The rice is traditionally topped by raw fish, cooked seafood, fish roe, egg, and/or vegetables such as cucumber, daikon radish, and avocado.
Microwave ovens do not cook food from the inside out. Microwave radiation penetrates food and causes direct heating only a short distance from the surface. This distance is called the skin depth. As an example, lean muscle tissue (meat) has a skin depth of only about 1 centimetre (0.39 in) at microwave oven frequencies.
== Words and phrases ==
The word 'fuck' did not come from Christianized Anglo-Saxon England and it is not any kind of acronym. The earliest recorded use of 'fuck' in English comes from about 1475, in the poem Flen flyys, where it is spelled fuccant (conjugated as if a Latin verb, meaning 'they fuck'). It is of Proto-Germanic origin, and is related to Dutch fokken and Norwegian fukka. Modern English was not spoken until the 16th century, and words such as 'fornication' did not exist in any form in English until the influence of Anglo-Norman in the late 12th century.
The word 'crap' did not originate as a back-formation of British plumber Thomas Crapper's surname. Nor does his name originate from the word 'crap', although the surname may have helped popularize the word. The surname 'Crapper' is a variant of 'Cropper', which originally referred to someone who harvested crops. The word 'crap' ultimately comes from Medieval Latin crappa, meaning 'chaff'.
The word 'gringo' is a pejorative term for an American. It did not originate during the Mexican-American War (1846–1848) or in the American Old West (~1865–1899); Nor did it originate during any of these times as a corruption of "Green go home!", falsely said to have been shouted at green-clad American troops. The word originally simply meant "foreigner", and is probably a corruption of Spanish griego, "Greek".
The phrase "sleep tight" did not originally refer to a supposed medieval or early modern practice of tightening feather mattresses with ropes. The word "tight" here simply means "soundly".
People during the Old and Middle English speaking periods never pronounced "the" as "ye". The idea that they did comes from confusion with the thorn, which in old print (þe or ye) often looked like a y.
The claim that a reporter, on assignment to Cuba, telegraphed William Randolph Hearst "...There will be no war. I wish to return" and Hearst responded, "Please remain. You furnish the pictures, and I'll furnish the war." Although this claim is included in a book, there is no evidence that the telegraph exchange ever happened, and substantial evidence that it did not.
The Dutch confections 'pepernoot' and 'kruidnoot' are often confused. Both are brown cookie-like desserts but kruidnoten are hard while pepernoten are soft and chewy.
== Science ==
=== Astronomy ===
It is commonly claimed that the Great Wall of China is the only human-made object visible from the Moon. This is false. None of the Apollo astronauts reported seeing any specific human-made object from the Moon, and even earth-orbiting astronauts can barely see it. City lights, however, are easily visible on the night side of Earth from orbit. Shuttle astronaut Jay Apt said "...the Great Wall is almost invisible from only 180 miles up".
Black holes, contrary to their common image, do not necessarily suck up all the matter around them. Were the Sun to be replaced by a black hole of the same mass, then the orbits of all the planets surrounding it would be unaffected. This is because "if you're outside the event horizon, you can just keep going around in circles around [a black hole], in exactly the same way that you can be in orbit around any other kind of mass".
Seasons are not caused by the Earth being closer to the Sun in the summer than in the winter. In fact, the Earth is actually farther from the Sun when it is summer in the Northern Hemisphere. Seasons are the result of the Earth being tilted on its axis by 23.4 degrees. As the Earth orbits the Sun, different parts of the world receive different amounts of direct sunlight. When an area of the Earth's surface is oriented perpendicular to the incoming sunlight, it will receive more radiation than it will when it is oriented at an angle to the incoming sunlight. In July, the Northern Hemisphere is tilted towards the Sun giving longer days and more direct sunlight; in January, it is tilted away. The seasons are reversed in the Southern Hemisphere, which is tilted towards the Sun in January and away from the Sun in July.
Meteorites are not necessarily hot when they reach the Earth. In fact, many meteorites are found with frost on them. A meteorite has been in the near-absolute zero temperature of space for billions of years, so the interior of it is very cold. A meteor's great speed is enough to melt its outside layer, but any molten metal will be quickly blown off, and the interior of the meteor does not have time to heat up because rocks are poor conductors of heat. Also, atmospheric drag can slow small meteors to terminal velocity by the time they hit the ground, giving them time to cool down.
=== Biology ===
DNA is not made of protein. DNA is instead a nucleic acid. However, DNA and protein work closely together. DNA is always accompanied by proteins in the chromatin of plants and animals. See protein biosynthesis for DNA's involvement in assembling protein. See also DNA replication and Ribonuclease.
Lemmings do not engage in mass suicidal dives off cliffs when migrating.
Bats are not blind. All bat species have eyes and can see. Further, not all bats can echolocate and these bats have excellent night vision (see megabat vs. microbat).
It is a common myth that an earthworm becomes two worms when cut in half. However, only a limited number of earthworm species are capable of anterior regeneration. When most earthworms are cut in half, only the front half of the worm (where the mouth is located) can survive, while the other half dies. Also, species of the planaria family of flatworms actually do become two new planaria when bisected or split down the middle.
According to urban myth, the daddy longlegs spider (Pholcus phalangioides) is the most venomous spider in the world, but the shape of their mandibles leaves them unable to bite humans, rendering them harmless to our species. In reality, they can indeed pierce human skin, though the tiny amount of venom they carry causes only a mild burning sensation for a few seconds. In addition, there is also confusion regarding the use of the name daddy longlegs, because harvestmen (order Opiliones, which are not spiders) and crane flies (which are insects) are also known as daddy longlegs, and share (also incorrectly) the myth of being venomous.
Poinsettias are not highly toxic. They are just mildly irritating to the skin or stomach, and may sometimes cause diarrhea and vomiting if eaten. Also, Poinsettias are not highly toxic to cats. According to the ASPCA, poinsettias may cause light to mid-range gastrointestinal discomfort in felines, with diarrhea and vomiting as the most severe consequences of ingestion.
The flight mechanism and aerodynamics of the bumblebee (as well as other insects) are actually quite well understood, in spite of the legend that calculations show that they should not be able to fly. In the 1930s a German scientist, using flawed techniques, postulated that bumblebees theoretically should not be able to fly, although he later retracted the suggestion.
Sharks can actually suffer from cancer. The myth that sharks do not get cancer was spread by the 1992 book Sharks don't get cancer by I. William Lane. Extracts of shark cartilage was sold as cancer prevention treatments. Reports of carcinomas in sharks exist, and current data do not allow any speculation about the incidence of tumors in sharks.
It is not harmful to baby birds to pick them up and return them to their nests, despite the common belief that doing so will cause the mother to reject them.
Bulls are not enraged by the color red, used in capes by professional matadors. Cattle are dichromats, so red does not stand out as a bright color. It is not the color of the cape that angers the bull, but rather the movement of the fabric that irritates the bull and incites it to charge.
Contrary to popular belief, dogs do not sweat by salivating. It is not true that dogs do not have sweat glands or have sweat glands only on their tongues. They do sweat, mainly through the footpads. However, dogs do primarily regulate their body temperature through panting.
==== Evolution ====
The word theory in the theory of evolution does not imply scientific doubt about its validity. The concepts of theory and hypothesis have specific meanings in science. While theory in colloquial usage may denote a hunch or conjecture, a scientific theory is a set of principles that explains observable phenomena in natural terms. "Scientific fact and theory are not categorically separable", and evolution is a theory in the same way as gravitation, or plate tectonics are theories.
Humans did not evolve from chimpanzees or any other modern-day primates. Humans and chimpanzees share a common ancestor that lived about seven million years ago. Humans are in the Hominidae (hominid and great ape) family, including chimpanzees, gorillas and orangutans. The common ancestor of humans and chimpanzees, which lived between 6 and 8 million years ago, evolved into two lineages. One line eventually became modern humans, and the other became the two living chimpanzee species.
Evolution is not a progression from inferior to superior organisms, because the words inferior and superior are undefined value judgements. Evolution also does not necessarily result in the evolution of complexity, though overall it has done so. A population can evolve to become simpler, having a smaller genome.
According to the California Academy of Sciences, only 59% of U.S. adults know humans and dinosaurs did not coexist. However, the last of the non-avian dinosaurs died 65.5 million years ago, after the Cretaceous–Tertiary extinction event, whereas the earliest Homo Genus (humans) evolved between 2.3 and 2.4 million years ago.
Evolution does not "plan" to improve an organism's fitness to survive. For example, an incorrect way to describe giraffe evolution is to say that giraffe necks grew longer over time because they needed to reach tall trees. Evolution does not see a need and respond to it. A mutation resulting in longer necks would be more likely to benefit an animal in an area with tall trees than an area with short trees, and thus enhance the chance of the animal surviving to pass on its longer-necked genes. Tall trees could not cause the mutation nor would they cause a higher percentage of animals to be born with longer necks. In the giraffe example, the evolution of a long neck may also have been driven by sexual selection. The idea would be that long necks evolved as a secondary sexual characteristic, giving males an advantage in "necking" contests over females. It is common for an adaptation to have more than one function.
Mammals did not evolve from reptiles, just as humans have not evolved from chimpanzees (above). Soon after the first vertebrate land-dwellers appeared, they split into two branches. The line leading to mammals (Synapsids) diverged from the line leading to reptiles (Sauropsids) about 320 million years ago, in the mid Carboniferous period. Only much later did the modern reptilian groups (lepidosaurs, turtles and crocodiles) emerge. Mammals are the only survivors of the synapsid line. The confusion over the origin of mammals comes from conflicting definitions of "Reptile". Under Linnaean taxonomy reptiles are all amniotes except mammals and birds, thus including the synapsids as well as the first basal amniotes. With the rise of classification based on phylogeny, the Sauropsida excludes basal amniotes and the synapsid line. The synapsids are popularly known as "mammal-like reptiles". An example is Dimetrodon, which is often thought of as a dinosaur, but is in fact neither a dinosaur nor closely related to modern reptiles.
=== Chemistry ===
Glass is not a high-viscosity liquid at room temperature: it is an amorphous solid, although it does have some chemical properties normally associated with liquids. Panes of stained glass windows often have thicker glass at the bottom than at the top, and this has been cited as an example of the slow flow of glass over centuries. However, this unevenness is due to the window manufacturing processes used in earlier eras, which produced glass panes that were unevenly thick at the time of their installation. Normally the thick end of glass would be installed at the bottom of the frame, but it is also common to find old windows where the thicker end has been installed to the sides or the top. In fact, the lead frames of the windows are less viscous than the panes, and if glass was indeed a slow moving liquid, the panes would warp at a higher degree.
=== Human body and health ===
==== The senses ====
Humans have more than five senses. Although definitions vary, the actual number ranges from 9 to more than 20. In addition to sight, smell, taste, touch, and hearing, which were the senses identified by Aristotle, humans can sense balance and acceleration (equilibrioception), pain (nociception), body and limb position (proprioception or kinesthetic sense), and relative temperature (thermoception). Other senses sometimes identified are the sense of time, itching, pressure, hunger, thirst, fullness of the stomach, need to urinate, need to defecate, and blood carbon dioxide levels.
==== Skin and hair ====
Windburn is not caused by wind (on a cloudy day). It is actually a sunburn.
Shaving does not cause terminal hair to grow back thicker or coarser or darker. This belief is based on the fact that hair which has never been cut has a tapered end, whereas after cutting there is no taper. Thus, the cut hair appears to be thicker, and feels coarser due to the sharper, unworn edges. The fact that shorter hairs are "harder" (less flexible) than longer hairs also contributes to this effect.
Hair and fingernails do not continue to grow after a person dies. Rather, the skin dries and shrinks away from the bases of hairs and nails, giving the appearance of growth.
Hair care products cannot actually "repair" split ends and damaged hair. They can prevent damage from occurring in the first place, and they can also smooth down the cuticle in a glue-like fashion so that it appears repaired, and generally make hair appear in better condition.
The gene for red hair is not going extinct. In August 2007, many news organizations reported that redheads would become extinct, possibly as early as 2060, due to the gene for red hair being recessive. Although redheads may become more rare, they will not die out unless everyone who carries the gene dies or fails to reproduce. This myth has been around since at least 1865, and often resurfaces in American newspapers. The proportion of genes do not change because an allele is recessive. That has no effect whatsoever on its frequency. See Hardy–Weinberg law
==== Nutrition, food, and drink ====
Eight glasses of water a day are not necessary to maintain health. Consuming things that contain water (e.g. juice, tea, milk, fruits or vegetables) also keeps a person hydrated.
Drinking normal levels of caffeinated beverages does not cause a net dehydration effect. The mild diuretic effect of caffeine is offset by the large amount of water in the caffeinated beverage.
Sugar does not cause hyperactivity in children. Double-blind trials have shown no difference in behavior between children given sugar-full or sugar-free diets, even in studies specifically looking at children with Attention-deficit hyperactivity disorder or those considered sensitive to sugar.
Alcohol does not make one warmer. The reason that alcoholic drinks create the sensation of warmth is that they cause blood vessels to dilate and stimulate nerve endings near the surface of the skin with an influx of warm blood. This can actually result in making the core body temperature lower, as it allows for easier heat exchange with a cold external environment.
Alcohol does not necessarily kill brain cells. Alcohol can however lead indirectly to the death of cells in the brain in two ways: (1) In chronic, heavy alcohol users whose brains have adapted to the effects of alcohol, abrupt cessation following heavy use can cause excitotoxicity leading to cellular death in multiple areas of the brain. (2) In alcoholics who get most of their daily calories from alcohol, a deficiency of thiamine can produce Korsakoff's syndrome, which is associated with serious brain damage.
A vegetarian or vegan diet can provide enough protein. In fact, typical protein intakes of ovo-lacto vegetarians, and of vegans, meet and exceed requirements. However, a strict vegan diet does require extra Vitamin B12 for good health.
==== Human sexuality ====
A popular myth regarding human sexuality is that men think about sex every seven seconds. In reality, this has not been measured, and as far as researchers can tell, this statistic greatly exaggerates the frequency of sexual thoughts.
Another popular myth is that having sex in the days leading up to a sporting event or contest is detrimental to performance. Many studies have shown that there is no physiological basis to this myth. Additionally, it has been demonstrated that sex during the 24 hours prior to sports activity can elevate the levels of testosterone in males, which potentially could enhance their performance.
==== The brain ====
Mental abilities are not absolutely separated into the left and right cerebral hemispheres of the brain. Some mental functions, such as speech and language, tend to activate one hemisphere of the brain more than the other. If one hemisphere is damaged at a very early age, however, these functions can often be recovered in part or even in full by the other hemisphere (see neuroplasticity). Other abilities such as motor control, memory, and general reasoning are served equally by the two hemispheres.
Until very recently medical experts believed that humans were born with all of the brain cells they would ever have. However, we now know that new neurons can be created in the postnatal brain. Researchers have observed adult neurogenesis in birds, Old World Primates, and humans. The newborn neurons migrate to the olfactory bulb and the dentate gyrus. They are believed to integrate into existing neural circuits. However, the function and physiological significance of adult-born neurons remains unclear. Some studies have suggested that post-natal neurogenesis also occurs in the neocortex, an idea that is disputed.
People do not use only ten percent of their brains. While it is true that a small minority of neurons in the brain are actively firing at any one time, the inactive neurons are important too. This myth has been commonplace in American culture at least as far back as the start of the 20th century, and was attributed to William James, who apparently used the expression metaphorically. Some findings of brain science (such as the high ratio of glial cells to neurons) have been mistakenly read as providing support for the myth.
==== Disease ====
Drinking milk or consuming other dairy products does not increase mucus production. As a result, they do not need to be avoided by those suffering from flu or cold congestion.
Warts on human skin are caused by viruses that are unique to humans (human papillomavirus). Humans cannot catch warts from toads or other animals; the bumps on a toad are not warts.
Vaccines do not cause autism. Although fraudulent research by Andrew Wakefield claimed a connection, repeated attempts to reproduce the results ended in failure, and the research was ultimately shown to have been manipulated.
Cracking ones knuckles does not cause osteoarthritis. Neither does simply exercising, as long as one does not get hurt.
Eating nuts, popcorn, or seeds does not increase the risk of diverticulitis. These foods may actually have a protective effect.
==== Miscellaneous ====
Waking sleepwalkers does not harm them. While it is true that a person may be confused or disoriented for a short time after awakening, this does not cause them further harm. In contrast, sleepwalkers may injure themselves if they trip over objects or lose their balance while sleepwalking. Such injuries are common among sleepwalkers.
Although it is commonly believed that most body heat is lost through a person's head, heat loss through the head is not more significant than other parts of the body when naked. This may be a generalization of situations in which it is true, such as when the head is the only uncovered part of the body. For example, it has been shown that hats effectively prevent hypothermia in infants.
Eating less than an hour before swimming does not increase the risk of experiencing muscle cramps or drowning. One study shows a correlation between alcohol consumption and drowning, but there is no evidence cited regarding stomach cramps or the consumption of food.
Drowning is often thought to be a violent struggle, where the victim waves and calls for help. In truth, drowning is often inconspicuous to onlookers. Raising the arms and vocalising are even usually impossible due to the instinctive drowning response. Waving and yelling (known as "aquatic distress") is a sign of trouble, but not a dependable one: most victims demonstrating the instinctive drowning response do not show prior evidence of distress.
It is a common misconception that hydrogen peroxide is a disinfectant or antiseptic for treating wounds. While it is an effective cleaning agent, hydrogen peroxide is not an effective agent for reducing bacterial infection of wounds. Further, hydrogen peroxide applied to wounds can impede healing and lead to scarring because it destroys newly formed skin cells.
=== Mathematics ===
Contrary to a widespread perception, the real number 0.999...—where the decimal point is followed by an infinite sequence of nines—is exactly equal to 1. They are two different ways of writing the same real number.
When a sequence of independent trials of a random process is observed a long run may occur. For example, when a roulette ball ended up on black 26 times in a row, and not even once on red,), the other outcome is often believed to be more likely for the next trial: it is thought to be "due". This misconception is known as the gambler's fallacy; in reality, by the definition of statistical independence, that outcome is just as likely or unlikely on the next trial as always—a property sometimes informally described by the phrase, "the system has no memory".
The correct answer to the Monty Hall Problem is that the contestant should indeed switch doors. The original problem is as follows: on a game show, there are three closed doors, one hiding a car and each of the other two doors concealing a goat. The contestant, wishing to win the car, selects a door. The door remains closed while the host, knowing where the car is hidden, proceeds to reveal a goat behind one of the remaining doors, and then offers the contestant a chance to switch his or her initial choice of door to the other closed door. Should the contestant switch? The correct answer is that the contestant should switch, as it doubles the chances of winning the car.
=== Physics ===
The Coriolis effect does not determine the direction that water rotates in a bathtub drain or a flushing toilet. The Coriolis effect caused by the Earth's daily rotation is too small to affect the direction of water in a typical bathtub drain. The effect becomes significant and noticeable only at large scales, such as in weather systems or oceanic currents. Other forces dominate the dynamics of water in drains. In addition, most toilets in the United States inject water into the bowl at an angle, causing a spin too fast to be significantly affected by the Coriolis effect.
Gyroscopic forces are not needed for a rider to balance a bicycle. Although gyroscopic forces are a factor, the stability of a bicycle is determined primarily by inertia, steering geometry, and the rider's ability to counteract tilting by steering.
It is not true that air takes the same time to travel above and below an aircraft's wing. This misconception is widespread among textbooks and non-technical reference books, and even appears in pilot training materials. In fact the air moving over the top of an airfoil generating lift is always moving much faster than the equal transit theory would imply, as described in the incorrect and correct explanations of lift force.
The idea that lightning never strikes the same place twice is one of the oldest and most well-known superstitions about lightning. There is no reason that lightning would not be able to strike the same place twice; if there is a thunderstorm in a given area, then objects and places which are more prominent or conductive (and therefore minimize distance) are more likely to be struck. For instance, lightning strikes the Empire State Building in New York City about 100 times per year.
A penny dropped from the Empire State Building will not kill a person or crack the sidewalk. The terminal velocity of a falling penny is about 30–50 miles per hour, and the penny will not exceed that speed regardless of the height from which it is dropped. At that speed, its energy is not enough to penetrate a human skull or crack concrete, as demonstrated on an episode of Mythbusters.
It is a common misconception that the color of water in large bodies, such as the oceans, is blue due to the reflections from the sky on its surface. Reflection of light off the surface of water only contributes significantly when the water surface is extremely still, i.e., mirror-like, and the angle of incidence is high, as water's reflectivity rapidly approaches near total reflection under these circumstances, as governed by the Fresnel equations. While relatively small quantities of water are observed by humans to be colorless, pure water has a slight blue color that becomes a deeper blue as the thickness of the observed sample increases. The blue tint of water is an intrinsic property and is caused by selective absorption and scattering of white light. Impurities dissolved or suspended in water may give water different colored appearances.
=== Psychology ===
Photographic or eidetic memory refers to the ability to remember images with extremely high precision—so high as to mimic a camera. However, it is highly unlikely that photographic memory exists, as to date there is no hard scientific evidence that anyone has ever had it. Many people have claimed to have a photographic memory, but those people have been shown to have good memories as a result of mnemonic devices rather than a natural capacity for detailed memory encoding. There are rare cases of individuals with exceptional memory, but none of them has a memory that mimics a camera.
Schizophrenia is not the same thing as Dissociative identity disorder, namely split or multiple personalities. Etymologically, the term "schizophrenia" comes from the Greek roots skhizein (σχίζειν, "to split") and phrēn, phren- (φρήν, φρεν-; "mind") and is a word proposed by the Swiss psychiatrist Eugen Bleuler. It may have given rise to this common misconception.
== Religion ==
=== Hebrew Bible ===
The forbidden fruit mentioned in the Book of Genesis is commonly assumed to be an apple, and is widely depicted as such in Western art, although the Bible does not identify what type of fruit it is. The original Hebrew texts mention only tree and fruit. Early Latin translations use the word mali, which can be taken to mean both "evil" and "apple". German and French artists commonly depict the fruit as an apple from the 12th century onwards, and John Milton's Areopagitica from 1644 explicitly mentions the fruit as an apple. Jewish scholars suggested that the fruit could have been a grape, a fig, wheat, or etrog. Likewise, the Quran speaks only of a forbidden "tree" and does not identify the fruit.
Nowhere in the Old Testament or the New Testament is Satan described as dwelling in or ruling over hell.
The Bible does not teach that humans can or will become angels after death. This myth has been proliferated by movies such as It's a Wonderful Life (1946) and Unlikely Angel (1996).
=== Buddhism ===
The historical Buddha was not obese. The "chubby Buddha" or "laughing Buddha" is a tenth century Chinese folk hero by the name of Budai. In Chinese Buddhist culture, Budai came to be revered as an incarnation of Maitreya, the Bodhisattva who will become a Buddha to restore Buddhism after the teachings of the historical Buddha, Siddhārtha Gautama, have died.
The Buddha is not a god. In early Buddhism, Siddhārtha Gautama possessed no salvific properties and strongly encouraged "self-reliance, self discipline and individual striving." However, in later developments of Mahāyāna Buddhism, notably in the Pure Land (Jìngtǔ) school of Chinese Buddhism, the Amitābha Buddha was thought to be a savior. Through faith in the Amitābha Buddha, one could be reborn in the western Pure Land. Although in Pure Land Buddhism the Buddha is considered a savior, he is still not considered a god in the common understanding of the term.
=== Christianity ===
There is no evidence that Jesus was born on December 25. The Bible never claims a date of December 25, but may imply a date closer to September.
Nowhere in the Bible does it say exactly three magi came to visit the baby Jesus, nor that they were kings, rode on camels, or that their names were Casper, Melchior and Balthazar. Three magi are supposed because three gifts are described, and artistic depictions almost always show three magi. Also, the wise men in the actual biblical narrative did not visit on the day Jesus was born, but saw Jesus as a child, in a house as many as two years afterwards (Matthew 2:11).
The Immaculate Conception is not synonymous with the virgin birth of Jesus, nor is it a supposed belief in the virgin birth of Mary, his mother. Rather, the Immaculate Conception is the Roman Catholic belief that Mary was not subject to original sin from the first moment of her existence, when she was conceived. The confusion stems from a misunderstanding of the term "immaculate," which means "without stain" (i.e. sinless). The concept of the virgin birth, on the other hand, is the belief that Mary miraculously conceived Jesus while remaining a virgin.
The doctrine of the perpetual virginity of Mary is not supported by canonical scripture, first appearing c.145 AD in the Gospel of James written several decades after the canonical ones. The Gospel of Matthew (1:24) implies that Mary and Joseph did indeed consummate a marriage after Jesus's birth, both Matthew (13:55) and the Gospel of Mark (6:3) indicate that Jesus had among his family four brothers (Joses, James, Jude and Simon) and an unspecified number of sisters. The Gospel of John makes reference to an unidentified number of Jesus's "brothers" associated with Mary and separate from his disciples. Nevertheless, the doctrine was held as truth by virtually all Christian authorities until the twentieth century, and remains a central tenet of the Roman Catholic Church.
Roman Catholics do not believe the pope is sinless. Catholic dogma does state that a teaching based on divine revelation stated by the pope is free from error. This does not mean that the pope or everything he says is free from error, even when speaking in his official capacity.
=== Islam ===
A fatwā is a non-binding legal opinion issued by an Islamic scholar under Islamic law. The popular misconception that the word means a death sentence probably stems from the fatwā issued by Ayatollah Ruhollah Khomeini of Iran in 1989 regarding the author Salman Rushdie, whom he stated had earned a death sentence for blasphemy. This event led to fatwās gaining widespread media attention in the West.
The word "jihad" does not always mean "holy war"; literally, the word in Arabic means "struggle". While there is such a thing as "jihad bil saif", or jihad "by the sword", many modern Islamic scholars usually say that it implies an effort or struggle of a spiritual kind. Scholar Louay Safi asserts that "misconceptions and misunderstandings regarding the nature of war and peace in Islam are widespread in both the Muslim societies and the West", as much following 9/11 as before.
== Technology ==
=== Inventions ===
George Washington Carver did not invent peanut butter, though he reputedly discovered three hundred uses for peanuts and hundreds more for soybeans, pecans, and sweet potatoes.
Thomas Crapper did not invent the flush toilet; it was invented by Sir John Harrington in 1596. Crapper, however, did much to increase its popularity and came up with some related inventions, such as the ballcock mechanism used to fill toilet tanks. He was noted for the quality of his products and received several Royal Warrants. Furthermore, his surname was not the origin of the word "crap" (see under Words and phrases above).
Thomas Edison did not invent the light bulb. He did, however, develop the first practical light bulb in 1880 (employing a carbonized bamboo filament), shortly before Joseph Swan, who invented an even more efficient bulb in 1881 (which used a cellulose filament).
Henry Ford did not invent either the automobile or the assembly line. He did help to develop the assembly line substantially, sometimes through his own engineering but more often through sponsoring the work of his employees. Karl Benz is credited with the invention of the first modern automobile, and the assembly line was invented before, several times.
Guglielmo Marconi did not invent radio, but only modernized it for public broadcasting and communication. No single person was responsible for the invention of radio.
James Watt did not invent the steam engine, The invention of the steam engine was a process of development and redevelopment. Watt developed the first commercially successful steam engine by greatly improving Newcomen's machine.
=== Transportation ===
Toilet waste is never intentionally dumped overboard from an aircraft. All waste is collected in tanks which are emptied on the ground by special toilet waste vehicles. A vacuum is used to allow the toilet to be flushed with less water and because plumbing cannot rely on gravity alone in an aircraft in motion. The infamous blue ice is caused by accidental leakages from the waste tank. Passenger trains, on the other hand, have historically flushed onto the tracks; however, modern trains usually have retention tanks on board the train.
== Related pages ==
MythBusters
Pseudoscience
== References ==
== Further reading ==
Diefendorf, David (2007). Amazing... But False!: Hundreds of "Facts" You Thought Were True, But Aren't. Sterling. ISBN 978-1-4027-3791-6.
Green, Joey (2005). Contrary to Popular Belief: More than 250 False Facts Revealed. Broadway. ISBN 978-0-7679-1992-0.
Johnsen, Ferris (1994). The Encyclopedia of Popular Misconceptions: The Ultimate Debunker's Guide to Widely Accepted Fallacies. Carol Publishing Group. ISBN 978-0-8065-1556-4.
Kruszelnicki, Karl; Adam Yazxhi (2006). Great Mythconceptions: The Science Behind the Myths. Andrews McMeel Publishing. ISBN 978-0-7407-5364-0.
Lloyd, John; John Mitchinson (2006). The Book of General Ignorance. Harmony Books. ISBN 978-0-307-39491-0.
Lloyd, John; John Mitchinson (2010). The Second Book of General Ignorance. Faber and Faber. ISBN 978-0-571-27285-3.
O'Conner, Patricia T.; Kellerman, Stewart (2009). Origins of the Specious: Myths and Misconceptions of the English Language. New York: Random House. ISBN 978-1-4000-6660-5.
Tuleja, Tad (1999). Fabulous Fallacies: More than 300 Popular Beliefs That Are Not True. Galahad Books. ISBN 978-1-57866-065-0.
Varasdi, J. Allen (1996). Myth Information: More Than 590 Popular Misconceptions, Fallacies, and Misbeliefs Explained!. Ballantine Books. ISBN 978-0-345-41049-8.
TITLE 2024 Atlantic hurricane season
The 2024 Atlantic hurricane season was an Atlantic hurricane season in the Northern Hemisphere. The season began on June 1, and will end on November 30. These days, chosen by convention, describe the usual points in each year when most subtropical or tropical cyclogenesis occurs in the Atlantic Ocean. The first system, Tropical Storm Alberto, developed on June 19, making it the latest first named storm since 2014.
The second storm of the season, Hurricane Beryl, was a rare June major hurricane, the earliest Category 5 Atlantic hurricane on record, and only the second recorded in July. Next came Tropical Storm Chris, which formed on the last day of June and quickly made landfall in Veracruz. Activity then quieted down across the basin for most of July after Beryl died out, with no new tropical cyclones forming due to the presence of the Saharan air layer across much of the Atlantic. In early August, Hurricane Debby developed in the Gulf of Mexico before making landfall in Florida and South Carolina. Shortly thereafter came Hurricane Ernesto, which impacted the Lesser Antilles, Puerto Rico, Bermuda, and parts of Atlantic Canada in mid-August. After a pause in activity in late August and September, Hurricane Francine formed in the Gulf, and made landfall in Louisiana, shortly afterwards.
On September 24, Hurricane Helene formed over the western Caribbean before moving toward the Big Bend region of Florida. It made landfall there on September 26, at Category 4 strength, before moving inland and dissipating over central Appalachia. Three days later, Hurricane Kirk formed in the Eastern Atlantic and rapidly intensified into a Category 4 hurricane before striking Europe as a post-tropical cyclone on October 9. On October 5, Hurricane Milton formed in the Gulf of Mexico and explosively intensified into the second Category 5 hurricane of the season, becoming the most intense Atlantic hurricane since Wilma in 2005 by pressure and the most intense since Dorian in 2019 by wind speed. Milton later made landfall near Siesta Key, Florida, on October 9, as a Category 3 hurricane. On October 19, both Tropical Storm Nadine and Hurricane Oscar formed. Nadine quickly made landfall in Belize while Oscar rapidly intensified into a Category 1 hurricane, becoming the smallest hurricane on record. It then made landfall in Cuba.
As of October 28, the storms of this season have collectively caused at least 372 fatalities and more than $190 billion in damage. Most of the fatalities are due to Beryl and Helene, while most of the damage is due to Helene and Milton.
== Seasonal summary ==
TITLE List of rivers of California
The following is a list of rivers in California, by location:
== Far North Coast ==
Rivers and streams between the Oregon border and Humboldt Bay that empty into the Pacific Ocean:
Smith River
Rowdy Creek
Klamath River
Trinity River
Salmon River
Scott River
Shasta River
Redwood Creek (Humboldt County)
Little River (Humboldt County)
Mad River
Maple Creek (California)
== Tributaries of Humboldt Bay ==
Jolly Giant Creek
Jacoby Creek
Eureka Slough
Freshwater Slough
Freshwater Creek
Elk River (California)
Salmon Creek (Northern Humboldt County)
== North Coast ==
Rivers and streams between Humboldt Bay and the Golden Gate that empty into the Pacific Ocean:
Eel River:
Van Duzen River:
Yaeger Creek
Bull Creek (Humboldt County)
Bear River (Humboldt County)
Mattole River
Noyo River
Big River
Albion River
Navarro River
Garcia River
Gualala River:
Wheatfield Fork
Russian River
== Tributaries of San Francisco Bay ==
Streams that empty into San Francisco Bay or its tributary bays, from north to south:
Petaluma River
Sonoma Creek
Napa River
Sacramento River:
Pit River
McCloud River
Hat Creek
Burney Creek
Fall River
Clear Creek
Cow Creek
Cottonwood Creek
Battle Creek
Mill Creek
Deer Creek
Big Chico Creek
Stony Creek
Butte Creek
Feather River
Fall River
Yuba River
Bear River
Dry Creek
American River
Rubicon River
Gerle Creek
Silver Creek
Slab Creek
Putah Creek
Cache Creek
Cache Slough
Miner Slough
Lindsey Slough
Lookout Slough
Steamboat Slough
Ulatis Creek
Horse Creek
San Joaquin River:
Mokelumne River
Cosumnes River
Bear River
Calaveras River
Stanislaus River
Tuolumne River
Clavey River
Merced River
Chowchilla River
Fresno River
Big Creek
Tulare Lake Basin—this region would overflow into the San Joaquin River during flood years
Kings River
Kaweah River
Tule River
Kern River
Pinole Creek
Alameda Creek
Coyote Creek
Guadalupe River
Stevens Creek
San Francisquito Creek
Redwood Creek (San Mateo County)
San Mateo Creek
== Central Coast ==
Rivers that empty into the Pacific Ocean between the Golden Gate and Point Arguello, from north to south:
San Gregorio Creek
Pescadero Creek
San Lorenzo River
Carbonera Creek
Zayante Creek
Bean Creek
Pajaro River
San Benito River
Elkhorn Slough
Salinas River
Estrella River
Nacimiento River
San Antonio River
Carmel River
Little Sur River
Big Sur River
Pfeiffer-Redwood Creek
San Luis Obispo Creek
Santa Maria River
Cuyama River
Sisquoc River
Santa Ynez River
== South Coast ==
Rivers that empty into the Pacific Ocean southeast of Point Arguello, from north to south:
Ventura River
Santa Ynez River
Santa Clara River
Castaic Creek
Piru Creek
Sespe Creek
Malibu Creek
Los Angeles River
Tujunga Wash
Arroyo Seco
Rio Hondo
San Gabriel River
Santa Ana River
Lytle Creek
Mill Creek
San Jacinto River (drains into Lake Elsinore but can overflow into the Santa Ana)
Aliso Creek
San Juan Creek
Santa Margarita River
San Diego River
San Luis Rey River
San Dieguito River
Sweetwater River
Otay River
Tijuana River
== Tributaries of the Gulf of California ==
Rivers that empty into the Gulf of California:
Colorado River
== Salton Sea ==
Rivers that empty into the Salton Sea:
Alamo River
New River
San Gorgonio River
Whitewater River
== Great Basin ==
Rivers in the Great Basin:
Amargosa River
Carson River
Lost River
Mojave River
Owens River
Rock Creek
Big Pine Creek
Bishop Creek
Susan River
Truckee River
Little Truckee River
Walker River
TITLE Water
Water (H2O) is a simple chemical compound made of two hydrogen atoms and one oxygen atom. It is clear, has no taste or smell, and is almost colorless. All living things need water to survive. Water molecules stick together because of hydrogen bonds. These bonds give water special properties. For example, water has high surface tension, and can dissolve many substances. Water exists in three forms on Earth: solid (ice), liquid (water), and gas (water vapor). The word "water" comes from the Old English word wæter.
About 71% of Earth’s surface is covered by water. Most of this water (about 97%) is in the oceans. This water is salt water, which we cannot drink or use for farming. Only 3% of Earth’s water is fresh water, and even that is not easy to get. 69% of all fresh water is frozen in glaciers and ice caps. 30% is stored underground in aquifers. Less than 1% is in lakes, rivers, and swamps. If you look at all the water on Earth, only about 1% can be used by us. And most of that water is found underground. Water is always moving in a cycle. This is called the water cycle. It includes:
Evaporation (water turns into vapor),
Transpiration (plants release water vapor),
Condensation (vapor forms clouds),
Precipitation (rain or snow falls),
Runoff (water returns to oceans and lakes).
Water has many unique abilities. One is that it expands when it freezes. This makes ice less dense than liquid water, so ice floats. Water also has a high specific heat capacity. It can absorb or lose a lot of heat without changing temperature much. This helps keep Earth's climate stable. Water’s surface tension lets it form droplets. It also lets small insects walk on water. Water is an excellent solvent. It can dissolve more substances than any other liquid. This is why it is called the "universal solvent." However, it cannot dissolve oily or nonpolar substances well. These special abilities come from water's polar nature and the hydrogen bonds between them.
Water is important for all living things. Every kind of life we know needs water to survive. This includes tiny living things like bacteria, archaea, and protists, and bigger ones like fungi, plants and animals. The human body is about 50-60% water. Water helps move nutrients, gases, and waste inside the body. Inside cells, water is where most chemical reactions happen. It also helps cells keep their shape. Water is needed for digestion in animals, and photosynthesis in plants. It also helps control body temperature. Without water, life could not exist. That is why water is one of the most important substances for all living things.
Water is also very important to the world economy. About 70% of the fresh water people use goes to farming. Water is used to grow crops and raise animals. Fish from oceans, lakes, and rivers are an important source of food. Many products, like crude oil and other goods, are moved around the world by ships through oceans, rivers, and canals. Water is also used to heat and cool buildings and machines. Because it can dissolve many substances, it is very useful in factories, cooking, and cleaning. Water can also be used to make electricity, using hydroelectric plants. It is also used for fun activities like swimming, boating, fishing, diving, ice skating, snowboarding, and skiing.
Many civilizations in history began near rivers or other places where they could get water easily. For example, Mesopotamia began between the Tigris and Euphrates rivers. Ancient Egypt depended on the Nile. The Indus Valley civilization started near the Indus River. Ancient Rome was built near the Tiber River. Even today, many big cities like London, New York, and Shanghai grew near water. Being close to rivers or oceans made it easier to trade and travel. Islands with good harbors, like Singapore, also became rich and powerful because ships could stop there easily. In dry places like North Africa and the Middle East, clean water has always been important. Having water often made the difference between a small village and a strong civilization.
Water is not just found on Earth. Scientists have discovered water in many places in space. Ice has been found on Mars, and even on the Moon. Some moons in our solar system, like Europa and Ganymede (around Jupiter), and Enceladus (around Saturn) may have liquid water under their icy surfaces. Water vapor has also been found in the atmosphere of some exoplanets. These are planets that orbit stars far away from our solar system. Water has even been found in clouds of gas and dust in space where new stars are being born.
== History ==
=== In the Universe ===
Shortly after the Big Bang, around 13.8 billion years ago, the universe was a hot, dense soup of particles. After 380,000 years, the universe expanded and cooled down enough for the first atomic nuclei to form in a process known as Big Bang nucleosynthesis. This produced mostly hydrogen, with smaller amounts of helium and trace amounts of lithium and beryllium. Oxygen and heavier elements did not yet exist, meaning water could not yet form.
Hundreds of millions of years later, the first stars were made from clouds of hydrogen and helium. Inside these stars, nuclear fusion began to produce heavier elements. In massive stars, fusion of lighter elements created heavier elements like carbon, nitrogen, and finally oxygen (a key ingredient for water). When these massive stars reached the end of their lives, they exploded as supernovae. This scattered those elements, including oxygen, into the interstellar medium.
Now that hydrogen and oxygen existed in the universe, they began to react and form water (H₂O). This happened mainly in molecular clouds. Here, water could form in two ways. On dust grains, hydrogen and oxygen atoms stuck to the surface can react to form water ice. In hot places inside the molecular cloud like around young stars, hydrogen and oxygen gas could react to form water vapor.
As molecular clouds collapsed to form new stars, protoplanetary disks (flat disks of gas and dust moving around the star) formed around these young stars. Water in these disks could be found as water vapor or ice. This depended on how close or far away the water was from the star. The "snow line" is a place far away from the star where it is cold enough for water to freeze and turn into ice. Inside this line, water stays as a gas, but beyond it, water becomes ice. This ice allowed particles to clump together and form planets. Water got trapped in icy planetesimals, comets, and asteroids. In the inner parts of star systems, it was usually too warm for ice, so most water there was in the form of vapor. Some water may have arrived later when comets or water-rich asteroids from the colder outer regions crashed into these inner planets, bringing ice that had formed far from the star.
On some planets and moons, the conditions were just right for water to exist as a liquid, solid (ice), or gas (vapor). Earth is the best and only example we know of. Because it is the right distance from the Sun and has a protective atmosphere, it has had oceans of liquid water for billions of years. Other places, like the moons Europa, Enceladus, and Ganymede, have oceans hidden under thick layers of ice. Mars has signs that it once had rivers and lakes long ago. Comets and asteroids still hold water from the early days of the solar system.
Today, water continues to be everywhere but mostly frozen or in vapor form. It found in molecular clouds, where stars and planets are still being made. It can also be found in interstellar space as ice on dust grains. It has also been found in the atmospheres of exoplanets. At the center of galaxies, massive amounts of water, billions of times the amount on Earth has been found around black holes. But, liquid water remains extremely rare, because it requires a very narrow set of conditions. Earth is unique because it contains liquid water on its surface.
=== On Earth ===
One of the biggest mysteries in astronomy is where Earth's water came from. Scientists are still trying to answer this question. Earth is special because it is the only rocky planet in our Solar System with oceans of liquid water on its surface. The other rocky planets, Mercury, Venus, and, Mars do not have large amounts of liquid water on their surface. Liquid water is important because every living thing we know needs it to survive. Earth has liquid water because it is in just the right spot in space. This spot is called the habitable zone. It is not too close to the Sun, where water would evaporate. It is also not too far away, where water would freeze. This perfect distance helps keep water in its liquid form on Earth.
There are many ideas about how Earth got its water. Most of these ideas fall into two main groups. One idea is that Earth already had the right ingredients (hydrogen and oxygen) when it formed, and those combined to make water. The other idea is that water came from space. It was carried by asteroids or comets that crashed into Earth after it formed. Some scientists think both of these ideas could be true. Earth might have gotten its water from more than one source. That makes the mystery a bit more complex, but researchers are trying their best to understand what happened in the early Solar System and how water ended up on our planet.
Earth formed about 4.54 billion years ago, after the Sun was born from a huge cloud of gas and dust. The leftover material from that cloud became the rest of the Solar System, including Earth. One idea is that Earth was born with everything it needed to create oceans, lakes, and rivers. But there is a problem. The early Solar System was extremely hot, especially near the center where Earth formed. Any water on the surface would have turned into gas and escaped into space. Another idea is that Earth’s water may have come from deep inside the planet. Water might have been trapped inside rocks deep underground when Earth was forming. This water was safe from the heat because it was hidden inside minerals in Earth's mantle. Over time, volcanoes released that water as steam. When the steam cooled, it turned into rain that helped form oceans and rivers.
Another idea is that Earth may have created its own water. Powerful space telescopes have seen young planets far away, that are surrounded by thick clouds of hydrogen gas. Scientists think that when Earth was very young, it might have had a lot more hydrogen in its atmosphere than it does today. Right now, Earth’s atmosphere is mostly nitrogen, and has almost no hydrogen. One idea suggests how hydrogen gas from the atmosphere could react with molten rock (magma) on the early Earth. This reaction could have produced large amounts of water. As the surface cooled and hardened, this water would have stayed on the planet, forming oceans and lakes.
A long time ago, the inner Solar System was a dangerous place. Between 4.0 and 3.8 billion years ago, the outer planets (Jupiter and Saturn) moved around and changed their orbits. Their powerful gravity sent icy space rocks flying toward the inner planets, including Earth. This time period is called the Late Heavy Bombardment. Many of these space rocks crashed into Earth, and scientists think they could have brought water with them. At first, people thought the water mainly came from comets. But space missions like Giotto (which visited Halley's Comet in 1986) and Rosetta (which visited another comet from 2014 to 2016) found that the water on comets is different from the water in Earth’s oceans. That means comets probably weren't the main source. Instead, scientists now think asteroids and meteorites brought most of the water. For example, a spacecraft called Hayabusa2 brought back pieces of an asteroid named Ryugu. Scientists found that the water trapped in its rocks looks like Earth’s ocean water. Ryugu is made of the same stuff as a type of meteorite called CI chondrites, which could have delivered up to 30% of the water in Earth’s oceans.
Scientists use ancient rocks to figure out when water first appeared on Earth. One kind of rock they use is called pillow basalt, which forms when a volcano erupts underwater. One of these rock was found in the Isua Greenstone Belt in Greenland. It is about 3.8 billion years old. This tells us that there was liquid water on Earth at that time. More of these very old rocks can be found in Canada, in a place called the Nuvvuagittuq Greenstone Belt. Some studies of these rocks also say there was water about 3.8 billion years old. Other studies suggest there was water 4.28 billion years. If there was water, like oceans, even earlier than that, we don't know yet. That might be because the Earth’s surface is always changing over time. Old rocks can be destroyed or buried through processes like plate tectonics and recycling of the crust, which can erase early signs of water. In 2020, scientists suggested that there might have been enough water to fill the oceans immediately after Earth formed.
To understand what Earth was like after it formed, scientists study rocks called zircons. Unlike most rocks, zircons are very tough. They can survive for billions of years, making them useful for studying early Earth. Zircons show that there was liquid water and an atmosphere 4.404 billion years ago, not long after Earth formed. This creates a problem, because the cool early Earth hypothesis says that Earth was cold enough to freeze water between 4.4 and 4.0 billion years ago. Other zircon studies from ancient Australian rocks suggest that plate tectonics may have started around 4 billion years ago. If that's true, Earth may have been similar to today, instead of being hot and covered in carbon dioxide. Plate tectonics helps trap carbon dioxide, which cools the planet and allows solid rock and liquid water to form.
=== In human civilization ===
In early human history, people survived by hunting animals and gathering plants. They often moved around and stayed close to sources of water or carried water around. But about 12,000 years ago, during the Neolithic revolution, humans started farming and raising animals. To do this, they needed a steady supply of water. Areas with rich soil and regular water made farming possible. This let people settle in one place and live in larger groups. Water also provided food, like fish and other water animals, and helped people travel using simple boats like canoes.
The first human civilizations began in river valleys, where there was plenty of fresh water and good soil for farming. For example, Mesopotamia, known as the "Cradle of Civilization," grew between the Tigris and Euphrates rivers. People there built irrigation canals to bring water to their crops. In Ancient Egypt, the Nile river was very important. It helped people grow food, raise animals, and move goods and people around. The Indus Valley civilization grew near the Indus River. They built advanced water systems, like wells, drains, and public baths. In Ancient China, the Yellow River helped northern China grow, but it also flooded a lot and caused many deaths. That is why it was called both "China’s pride" and "China’s sorrow." In Ancient Rome, people built aqueducts. They were long channels that carried water from far away places into cities. This water was used for farming, public baths, toilets, and even homes.
In the earliest civilizations, rivers and seas were very important for transport and trade. They made it easier to move heavy goods over long distances. In Mesopotamia, the Tigris and Euphrates rivers connected cities like Ur and Babylon. In Egypt, the Nile River helped people trade from Nubia in the south all the way to the Mediterranean Sea. The Phoenicians were great sailors who built strong ships and set up trade colonies around the Mediterranean. Busy ports like Alexandria, Athens, Tyre, and Carthage became rich and full of culture because of sea trade. In Medieval Europe, rivers like the Danube, Rhine, and Seine helped create strong trade networks. Cities like Venice and Genoa became powerful by trading across the sea. In the 1400s, countries like Portugal, Spain, England, and the Netherlands began exploring the world by sea. Christopher Columbus’s voyages opened up the Atlantic Ocean. This connected Europe, Africa, and the Americas in what became known as the Columbian Exchange. Later, the British and the Dutch East India Company built huge trade empires using powerful ships and ocean routes.
As cities got bigger with more people, their water systems could not keep up with the growing population. This led to more disease outbreaks. This was before people understood how germs worked. Diseases like typhoid, cholera, and dysentery spread quickly through dirty water and killed millions of people over the centuries. In Medieval Europe, cities did not have good plumbing. Waste flowed through open sewers in the streets and often mixed with drinking water. This caused many deadly epidemics. In the 1800s, London had several major cholera outbreaks. At first, people thought the disease came from bad air, called “miasma.” But in 1854, a doctor named John Snow proved that cholera was actually spread through dirty water. He traced the outbreak to a single water pump on Broad Street. People learned that having water was not enough. It had to be clean and kept away from waste. In the late 1800s and early 1900s, cities began improving public health by building better water systems. Engineers created piped water networks, storage tanks, and pumping stations to bring clean water to homes. They also built underground sewer systems to safely carry away human waste. Cities like London, Paris, and New York only made these changes after big epidemics showed how serious the problem was. New water treatment methods like sand filtering and adding chlorine helped kill germs and made water safer to drink.
A long time ago, ancient Greek thinkers like Thales of Miletus believed that water was the basic building block of everything in the world. Around 250 BCE, Archimedes used water to figure out the volume of an object by seeing how much water it pushes away when put in water. During the Renaissance, Leonardo da Vinci studied how water flows and how it helps wear away rocks over time. He helped build canals and other things to help control water. Galileo Galilei looked at why some things float on water and others do not. He also studied tides, the regular rising and falling of the sea. By the late 1700s, Antoine Lavoisier figured out that water was not an element, but a compound made from hydrogen and oxygen.
Today, about 70% of all the freshwater we use around the world goes to agriculture, making farming the biggest user of water. Plants need water to grow, animals need it to live, and irrigation helps farmers grow crops even in dry areas. In modern times, how much water a country has can affect whether it can grow enough food for its people or if it has to buy food from other countries. Places with lots of water, like the United States, Brazil, China, and India, are major food producers. These countries grow extra crops like wheat, corn, soybeans, and rice, and sell them to other countries. Having lots of rain, rivers, underground water, and good systems like dams and canals gives these countries a big advantage. But countries with very little water, like Saudi Arabia, Qatar, the UAE, and Kuwait have trouble growing enough food. They do not have enough freshwater or good land for farming, so they import most of their food from other places. Fish are also an important source of food for the world. Over 1 billion people depend on fish as their main source of protein, especially in places near rivers and oceans. Fish farming, called aquaculture, has allowed us to raise fish instead of looking for them.
Even today, oceans and rivers are still the main way we move goods around the world. In fact, about 80% of all global trade by volume travels by sea. Oceans, rivers, and canals are great for moving things like fuel, raw materials, and products because it is cheaper than using trucks or planes. Some water routes are especially important. The Suez Canal, Panama Canal, Strait of Hormuz, and Strait of Malacca are key paths for global trade. Large ports like those in Shanghai, Rotterdam, Singapore, and Los Angeles help grow their countries' economies. Big rivers like the Mississippi in the U.S., the Yangtze in China, and the Danube in Europe are also important. They help move large amounts of goods inside countries cheaply.
Modern water systems help bring clean water to billions of people around the world. Dams and reservoirs store water for drinking, farming, flood control, and even to make electricity. Famous examples include the Hoover Dam in the U.S. and the Three Gorges Dam in China. Pipelines and aqueducts move water from places that have a lot of it to places that do not have much and big cities. For example, Los Angeles gets much of its water from places far away. In very dry regions like the Middle East, Israel, and parts of Australia, desalination plants turn salty seawater into fresh drinking water. But this process uses a lot of energy. Wastewater treatment plants clean dirty water from homes and businesses so it does not pollute rivers and lakes. Sometimes, this cleaned water is reused for farming or industry.
The world still faces big problems with water. More than 2 billion people live in places where there is not enough water. In areas like India, the southwestern U.S., and the Middle East, people are using up groundwater faster than it can be replaced. Because of this, there might not be enough water in the future. Climate change is making things worse. It causes longer droughts, changes where and when rain falls, and reduces the amount of snow in mountains. Snow is important because it slowly melts releasing water into rivers over time. Pollution is also a big problem. Factories, farms, and untreated sewage can make rivers and lakes dirty. Rising sea levels are pushing saltwater into underground water supplies near the coasts, making them unsafe to drink. More powerful storms are causing floods that city drainage systems can not handle. Because of this, we must protect and manage water carefully for the future.
== Properties of water ==
Water is a chemical substance. It is made of two hydrogen atoms and one oxygen atom. Its chemical formula is H₂O. These atoms are held together by something called a covalent bond. At room temperature and normal pressure, water is a liquid. It has almost no color, taste or smell. Water is often called the "universal solvent" because it can dissolve more substances than any other liquid. But it cannot dissolve nonpolar substances like oil very well. Water is also the only common material on Earth that can naturally exist as a solid, liquid, and gas.
A water molecule looks like a bent “V” shape. The angle between the two hydrogen atoms is about 104.5°. This shape happens because of how electrons are arranged around the oxygen atom. Oxygen has six outer (valence) electrons. It uses two of them to bond with two hydrogen atoms (one for each). The other four electrons stay in two pairs, called lone pairs, that do not bond with anything. According to VSEPR theory, all these pairs of electrons want to stay as far apart as possible. This creates a shape like a tetrahedron with four regions: two bonding pairs and two lone pairs. But lone pairs take up more space and push harder than bonding pairs. They push the hydrogen atoms closer together, so the angle becomes smaller than the usual 109.5° of a perfect tetrahedron. That is why the water molecule is bent instead of straight, and why the bond angle is 104.5°.
=== Hydrogen bonds ===
A water molecule (H₂O) has one oxygen atom and two hydrogen atoms. Oxygen is much more electronegative than hydrogen. This means it attracts electrons closer to itself much more than hydrogen. So, when oxygen and hydrogen share electrons in a water molecule, the electrons spend more time near the oxygen atom. This gives the oxygen atom a partial negative charge (δ⁻). And the hydrogen atoms gains a partial positive charge (δ⁺). So, the water molecule now has a positive side and a negative side. Because of this, the positive hydrogen of one water molecule is attracted to the negative oxygen of another. This attraction is called a hydrogen bond. It is not as strong as a normal chemical bond (like a covalent bond). But, it is strong enough to hold water molecules loosely together. Hydrogen bonding explains many of water’s unusual properties. For example, water's high boiling and melting points, high surface tension, the ability of ice to float on water, and the ability to dissolve many substances.
Water (H₂O) is a liquid at room temperature. This might seem normal until you compare it to similar substances. Water belongs to a group of compounds called hydrogen chalcogenides. These are made when hydrogen bonds with elements from the same family as oxygen: sulfur, selenium, and tellurium. This includes hydrogen sulfide (H₂S), hydrogen selenide (H₂Se), and hydrogen telluride (H₂Te). But, while water is a liquid, the others are all gases at room temperature. The reason is hydrogen bonding. Oxygen is very electronegative (it strongly pulls on electrons) and is small in size. Because of this, water molecules can form strong hydrogen bonds. Each water molecule can form up to four hydrogen bonds with its neighbors. This creates a kind of "stickiness" that holds the molecules together and makes it harder for them to break apart and turn into a gas. That is why water has a high boiling point of 100°C (212°F) for such a small molecule. The other chalcogens (sulfur, selenium, and tellurium) are larger but less electronegative than oxygen. In hydrogen sulfide (H₂S), hydrogen selenide (H₂Se), and hydrogen telluride (H₂Te), the bonds between hydrogen and the other elements are weaker. These molecules do not form strong hydrogen bonds. Instead, they only have weak van der Waals forces, which are easy to break. So these substances boil at much lower temperatures. Hydrogen sulfide (H₂S) boils at –60°C. Hydrogen selenide (H₂Se) boils at –41.5°C. Hydrogen telluride (H₂Te) boils at –2.2°C. That is why they are gases at room temperature, while water is a liquid.
==== Cohesion and adhesion ====
Water molecules stick to each other. This is called cohesion. This happens because each water molecule can form hydrogen bonds with its neighbors. Inside a drop of water, each molecule is pulled in all directions by the other water molecules around it. But at the surface, there are no water molecules above. The hydrogen bonds at the surface of water pulls molecules tightly together, forming a sort of "skin" on the surface. This is called surface tension. This is why water forms droplets. It is also why small insects, like water striders, can walk on water. It is also why small objects like a needle can float if placed gently on water.
Water molecules can stick to other surfaces. This is called adhesion. This especially happens to surfaces that are polar or charged, like glass, plant cell walls, or soil particles. Water's adhesion can be seen when water climbs up the side of a glass container, forming a curved surface called the meniscus. It can also be seen as water spreads out on a leaf or sticks to surfaces like spider webs. Whether water forms flat puddles or round beads depends on the balance between cohesion and adhesion. If water sticks more to the surface, it spreads out. If water sticks more to itself, it forms beads.
Water can climb up a thin tube or narrow space. This is called capillary action. It happens because adhesion pulls water molecules to the sides of a thin tube or pore, while cohesion pulls other water molecules along with it. In plants, capillary action helps water move from the roots to the leaves. As water evaporates from the leaves, it pulls more water up behind it. Adhesion helps the water stick to the sides of the plant's tubes. Cohesion keeps the water molecules connected like a chain, so they move upward together. This allows them to move up against gravity.
==== Heat and water ====
Water is very good at staying at the same temperature. It does not heat up or cool down quickly. This is because water has a high specific heat capacity. That means it takes a lot of heat to make water warmer, and it cools down slowly too. Specific heat is the amount of heat needed to change the temperature of 1 gram of a substance by 1°C. For water, this is 1 calorie. That is much higher than most other common substances. For example, alcohol only needs 0.6 calories to do the same, so it heats up faster than water.
If you touch a metal pot with warm water inside, the metal might feel hotter than the water. That is because metal heats up faster than water. Water takes longer to warm up because water molecules are held together by hydrogen bonds. When heat is added, much of the energy goes into breaking the hydrogen bonds between water molecules. Once those bonds are broken, the molecules can move faster, and the temperature rises. So instead of heating up quickly, water stores heat by breaking the hydrogen bonds first. When water cools down, the hydrogen bonds form again and release heat. This helps keep temperatures steady. Oceans and lakes can absorb heat from the sun during the day or in summer and release it slowly at night or in winter. That is why places near water usually have milder temperatures. Water’s high specific heat also keeps the ocean from getting too hot or too cold. This is very important for ocean life. And because our bodies are mostly made of water, this also helps us keep a steady body temperature.
Water molecules usually stay close together. But if some molecules move fast enough, they can break free and escape into the air as gas. This process is called evaporation. Even at low temperatures, the fastest molecules can still escape. This is why a glass of water will slowly disappear over time. Heating water makes its molecules move faster, so it evaporates faster too. The heat of vaporization is the amount of heat needed to turn 1 gram of liquid water into gas. For water, it takes about 580 calories to evaporate just 1 gram at 25°C. This is nearly double the amount needed for ammonia and alcohol. Water’s high heat of vaporization is because of hydrogen bonds. Water molecules are held together through hydrogen bonds. To vaporize water, these bonds must be broken, which takes a lot of energy. The energy does not raise the temperature. It goes into breaking the hydrogen bonds. That is why water takes a long time to boil and releases a lot of heat when it condenses.
This high heat of vaporization has important effects on Earth. Tropical oceans take in a lot of heat from the Sun. Some of this heat is used to evaporate water. When that water vapor travels to cooler places and turns back into rain, it releases heat. This helps balance Earth’s climate and spread heat around the planet. Evaporation also cools things down. When water evaporates, the fastest (hottest) molecules leave first. This lowers the temperature of the water that is left behind. This is called evaporative cooling. It helps keep lakes, plants, and animals from getting too hot. When we sweat, the sweat takes heat from our skin as it evaporates. This is why sweating cools down. On hot, humid days, the air already has a lot of water vapor. That makes it harder for sweat to evaporate, so we feel even hotter. Some animals that cannot sweat, like elephants, cool themselves by spraying water on their skin.
It also takes a lot of energy to melt ice. This is called the heat of fusion. The heat of fusion is the amount of energy needed to change 1 gram of a substance from solid to liquid at its melting point. For water, this is 334 joules per gram (J/g). That is higher than most other substances, especially for a molecule as small as water. When water freezes into ice, its molecules form a crystalline structure held together by hydrogen bonds. To melt ice, you need enough energy to break many of these bonds. The heat added goes into breaking these bonds, but does not increase the temperature. The water that is produced also remains at 0°C until all of the ice is melted. The same amount of energy needed to melt ice could warm that same ice from –160°C all the way up to 0°C. Ice and snow can take in heat without melting right away. This helps keep temperatures from changing too quickly. In cold places like the North and South Poles or high mountains, this helps keep the temperature more steady. Before we had refrigerators, people used ice to keep food cool because it stayed frozen for a long time.
==== Density of ice ====
Water is one of the only substances that becomes less dense when it freezes. This means that ice floats on water. Most substances get smaller and denser when they freeze. But water is different. It expands (or gets bigger) when it freezes. This strange behavior happens because of hydrogen bonds. At temperatures above 4°C, water acts like most liquids. It expands when heated and shrinks when cooled. But between 4°C and 0°C, something strange happens. As the water gets colder, the molecules slow down. They do not have enough energy to break the hydrogen bonds between them. At 0°C, the molecules line up into a solid crystal shape. Each molecule connects to four others with hydrogen bonds. These bonds hold the molecules further apart. So the ice takes up more space than the liquid water, even though it has the same number of molecules. That is why ice is about 9% less dense than water at 4°C. When ice melts, the bonds break and the molecules move closer together. Water is densest at 4°C. It becomes less dense if it gets warmer or cooler from that temperature.
The fact that ice floats is very important for life on Earth. If ice sank, lakes and oceans could freeze all the way to the bottom. This would make it hard or even impossible for fish and other living things to survive. Instead, ice floats on top, and acts like a blanket. This helps keep the water below from freezing. Fish and other organisms can stay alive under the ice. Also, floating ice provides homes for animals like polar bears and seals.
==== Water as a universal solvent ====
When you drop a sugar cube into a glass of water, the sugar slowly dissolves and spreads out. This creates a mixture. This type of mixture is called a solution. In a solution, the solvent is the substance that does the dissolving (in this case, water), and the solute is the substance that gets dissolved (the sugar). If water is the solvent, the solution is called an aqueous solution.
Water is a very good solvent. Because of this, it is often called the "universal solvent". This is because it can dissolve more substances than any other substance. This happens because water molecules have slightly positive and negative parts. These parts attract other charged or polar substances. For example, when you add salt (sodium chloride, or NaCl) to water, it breaks into sodium (Na⁺) and chloride (Cl⁻) ions. The negative side of water pulls on the sodium, and the positive side pulls on the chloride. Water molecules surround each ion. They then pull them away from the salt crystal. After that, they spread them out in the water. This group of water molecules around an ion is called a hydration shell. Other ionic compounds, like potassium chloride, also dissolve in water this way. Seawater is full of dissolved ions like these. But a substance does not have to be made of ions to dissolve in water. Polar molecules like sugar can also dissolve. This is because they can form hydrogen bonds with water. Even large molecules, like proteins, can dissolve in water if they have polar or charged areas on their surfaces.
Water is the main solvent for living things. Many important substances are dissolved in the water in blood, plant sap, and cells. Any substance that mixes well with water is called hydrophilic (water-loving). Some hydrophilic substances do not dissolve in water. For example, some molecules in cells are too big to dissolve. Another example is cotton. Cotton is made up of giant molecules of cellulose. Cellulose does not dissolve in water. It has lots of positive and negative parts that can form hydrogen bonds with water. Water sticks to the cellulose. That is why cotton towels drys things well, but does not dissolve in the washing machine. Plants also use cellulose in the tubes that carry water from roots to leaves. Water sticks to the hydrophilic walls of these tubes, helping it move upward against gravity. On the other hand, substances that do not mix with water are called hydrophobic (water-fearing). These include oils and fats. They don't dissolve because they do not have charges that attract water. That is why oil and water do not mix. Hydrophobic molecules can be found in cell membranes. Without them, cells would dissolve in water. Life would be impossible.
=== States of water ===
Water can exist in three main forms: solid, liquid, and gas. These are called states or phases. Which one water is in depends on the temperature and pressure.
When people say "water" in everyday life, they usually mean liquid water. This is the form that comes from taps, fills oceans, rivers, and lakes, and is used for drinking, cooking, and cleaning. Liquid water is the most common form found on Earth's surface. When water gets cold enough, it freezes and becomes a solid called ice. Ice can be in the form of hard cubes (like in your freezer) or soft, loose crystals, like snow. There are also other strange kinds of ice. These are often found in extreme environments like outer space deep inside Uranus. When water gets hot enough, it turns into a gas called water vapor. This is what we see as steam rising from boiling water.
Water can also exist in a very strange state called a supercritical fluid. This only happens at extremely high temperatures above (374°C or 705°F) and very high pressures (above 22.064 megapascals). Here, water acts like a gas and a liquid at the same time. It can flow like a liquid and spread out like a gas. Supercritical water is useful because it can dissolve many things that normal water cannot. It can dissolve nonpolar organic compounds like oil. This strange state of water does not happen naturally on Earth’s surface. But it can happen deep in the ocean. One example is near hydrothermal vents. This happens at around 2200 meters deep. The ocean is much deeper than that on average at about 3800 meters.
=== Changing states ===
A phase diagram is a special graph. It shows how a substance like water changes between solid, liquid, and gas depending on the temperature and pressure. On this graph, the bottom (horizontal) line shows temperature. The side (vertical) line shows pressure. The graph is divided into three parts. One part shows where water is a solid (ice). Another part shows where it is a liquid (water). And another part shows where it is a gas (steam). There is a special point on the graph called the triple point. At this temperature and pressure, water can exist as a solid, liquid, and gas at the same time. For water, this happens at 0.01 °C and a pressure of 611.657 pascals.
At normal air pressure (1 atmosphere), water freezes into ice at 0 °C (32 °F) and boils into steam at 100 °C (212 °F). The freezing point is the temperature at which water turns to ice. The boiling point is the temperature at which water turns into gas. Water does not need to be boiling to become gas. Even at low temperatures, some water molecules can move fast enough to evaporate. This is why a glass of water when left alone will slowly dry out. But when water is heated, the molecules move faster and evaporate quicker. When water reaches 100 °C, bubbles of water vapor form inside the liquid. These bubbles rise to the top and release steam into the air.
Water vapor (gas) can turn directly into ice without becoming liquid first. This is called deposition. You can see this when frost forms on cold windows. It also happens when snowflakes form in clouds. In clouds, tiny pieces of dust or pollen help water vapor turn straight into ice. The opposite of deposition is called sublimation. This is when ice turns straight into water vapor without becoming a liquid. One use of sublimation is in freeze-drying food. a method of preserving food. First, the food is frozen. Then it is put into a vacuum (a space with no air). The ice inside the food turns into vapor. This leaves the food dry, without using heat.
Water usually freezes at 0 °C (32 °F) at normal air pressure. But in special conditions, pure water can stay liquid even it is colder than that. If it is not shaken or disturbed, it can cool all the way down to about –42 °C (–44 °F) without freezing. This is called supercooling.
The melting and boiling points of water change with pressure. For most things, if you add more pressure, they melt at a higher temperature. But water is different because ice is less dense than liquid water. That is why ice floats. When pressure is added to ice, the melting point actually goes down. That means ice can melt even when it is colder than 0 °C if there is enough pressure. This can happen deep under a glacier. The heavy ice on top pushes down with a lot of pressure. This pressure can melt the ice under it, even though it is very cold. That is how lakes can form under glaciers.
Steam (which is water in gas form) takes up much more space than liquid water. That means it is less dense. When the pressure is high, it becomes harder for water to boil, so it needs to be hotter to turn into steam. In places with a lot of pressure, water can stay as a liquid even when it gets hotter than 100 °C (212 °F), which is the normal boiling point. For example, in geysers like Old Faithful, water can get over 205 °C (401 °F) without boiling. And near underwater volcanoes called hydrothermal vents, water can reach 400 °C (752 °F) and still stay liquid.
At sea level, water boils at 100 °C (212 °F). But when you go up higher like up the mountains, the air pressure gets lower. When pressure is lower, water boils at a lower temperature. For every 274 meters (or about 900 feet) you go up, the boiling point goes down by about 1 °C. For example, at 274 meters (about 900 feet), the boiling point becomes 99°C (210.2°F) instead of 100°C (212°F). That is why food takes longer to cook at higher altitudes. The water boils before it gets really hot. A pressure cooker works the opposite way. It traps steam inside, which raises the pressure. This lets water boil at a higher temperature, so food cooks faster. In places with no air at all, like in a vacuum, water can even boil at room temperature. This is because there is no pressure holding the water molecules together.
=== Taste and odor ===
People often say that water has no taste or smell. But in real life, most of the water we drink has some taste or smell. This is because there are usually tiny amounts of other substances dissolved in the water. Pure water does not have a taste, but our tongues can tell if something is mixed in. For example:
Salts in water can give it a “mineral” taste, like water from springs.
Water that is very acidic tastes sour.
Water that is very basic (alkaline) tastes bitter.
Tap water often has chlorine added to kill germs. This can give it a chemical or medicine-like taste.
Metals like iron or copper can cause a metallic taste. This can be found in water from old pipes.
Even tiny amounts of these substances can change the taste. How strongly people taste them can depend on how cold or warm the water is and even a person's genes.
Water can smell earthy or musty. This often come from natural chemicals like geosmin or 2-methylisoborneol (MIB) made by algae or bacteria in lakes and rivers.
A rotten egg smell means the water might have hydrogen sulfide gas in it.
Tap water might smell a little like chlorine, from the treatment process.
Some of these smells are so strong that the human nose can detect them even in very small amounts. Some animals, like frogs, can even smell water itself.
=== Mechanical properties ===
Water is often called incompressible. This means that even if you push on it really hard, it doesn't shrink much. For example, at the bottom of the ocean, about 4 kilometers (2.5 miles) deep, the pressure is 400 times greater than at sea level. But water only gets about 1.8% smaller. This happens because water has a high bulk modulus (about 2.2 gigapascals). This means it resists being squeezed.
Viscosity is how easily a liquid flows. Water has low viscosity, so it flows quickly and easily, like in rivers or through pipes. Honey or syrup have high viscosity, so they flow slowly and are thick. Water flows smoothly through rivers, pipes, and the human body (like in blood vessels and cells). Viscosity changes with temperature. When a liquid gets warmer, it becomes thinner and flows more easily. When it gets colder, it becomes thicker and flows more slowly. So, warm water flows faster, and cold water flows slower. Water is called a Newtonian fluid. This means its viscosity stays the same even if you stir it fast or slow.
Sound travels through water at about 1,400 to 1,540 meters per second, depending on how warm, salty, or deep the water is. That is over 4 times faster than in air. Whales use sound to talk and find food underwater. Humans use tools like sonar to find things under the sea.
=== Electrical properties ===
Water is a polar molecule. This means it has slightly charged ends. In water molecules, the hydrogen atoms have a small positive charge, and the oxygen atom has a small negative charge. This happens because oxygen pulls electrons closer to itself. That is because oxygen is more electronegative. It likes to attract electrons more than hydrogen does. This polarity helps water surround and pull apart other substances, especially those made of charged particles, like table salt (NaCl). When salt is added to water, the negative part of water (the oxygen) surrounds the positive sodium ions (Na⁺). The positive part (the hydrogen) surrounds the negative chloride ions (Cl⁻). This helps break the salt apart and keep the ions floating around in the water.
Water also has a high dielectric constant. It is about 80 at room temperature. That is much higher than most other liquids. This means water can reduce the electrical attraction between opposite charges. As a result, ions (like those from salt) can separate more easily in water. This is why it is so good at dissolving electrolytes. This makes it easier for ions to stay separate and move around freely. This is important for conducting electricity in biological and chemical systems. Thanks to its polarity and dielectric nature, water is one of the best solvents in the world. That is why it is called the "universal solvent".
Water can go through a special process called autoionization (also called self-ionization). This means that two water molecules can react with each other to make two new particles: a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). One water molecule, takes a hydrogen from the other becoming a hydronium ion while the other is left with one hydrogen becoming a hydroxide ion.
The reaction looks like this:
H2O + H2O H3O+ + OH−
This reaction does not happen often. At room temperature (25 °C), only a tiny number of water molecules do this. In pure water, the amounts of H₃O⁺ and OH⁻ are each 1 × 10⁻⁷ mol/L (moles per liter). That tiny amount makes water neutral and gives it a pH of 7. The pH scale, which tells us if something is acidic or basic, is based on this. Because there are so few ions, pure water does not conduct electricity well. That means pure water is more like an insulator than a conductor.
But water can dissolve ionic substances like salt very well. When you add even a little table salt (NaCl) to water, it releases lots of ions. The conductivity goes up a million times. That is why tap water and seawater conduct electricity so well. Seawater, for example, has ions like Na⁺, Cl⁻, and Mg²⁺, making it highly conductive. This matters in real life. Distilled water, which has no ions, can't carry electricity. But regular water, with minerals or salts in it, can carry electric current. This is important in batteries, electrolysis, and even in cells in your body.
=== Optical properties ===
In small amounts, water looks clear, but pure water actually has a slight blue tint. You can see the blue color more easily when you look at a large amount of water, like in a swimming pool, lake or ocean. The color comes from the way water interacts with light. Pure water absorbs some colors of light more than others. Those colors include the red, orange, and yellow parts of sunlight. This leaves more blue light to be reflected into our eyes. This is why water looks blue. You cannot see this in a glass of water. You can only see this when you are looking at deeper water, like in a swimming pool or lake. The deeper the water, the more light gets absorbed, and the more the blue color is seen. If water has something dissolved in it or tiny particles floating in it, the color can change. For example, algae and organic matter can make water look green or brown. Minerals and sediments in the water can change its color. Tannins from decaying plants can give water a tea-like, brownish color.
Visible light can mostly go through water. Blue and green light go the deepest in water. On the other hand, red, orange, and yellow light gets absorbed by the water, so they do not go very deep. In clear ocean water, sunlight can reach down to about 200 meters. This upper layer is called the photic zone. It is where there is enough light for plants and tiny algae like phytoplankton to do photosynthesis. Deeper than that, there is not enough light for plants to do photosynthesis.
Water bends light because it has a higher refractive index than air. The refractive index of water at room temperature (20°C or 68°F) is about 1.333. The refractive index of air is about 1.0. This means that when light enters water from the air, it slows down and bends. This is called refraction. It is this bending of light that causes a straw to look bent or broken in a glass of water. It is also why things under water look closer or larger than they actually are. Ice has a slightly lower refractive index (about 1.31). Because of this, light bends a bit less when passing through ice than through liquid water. The refractive index of water is similar to some liquids like ethanol and alkanes. But, it is lower than substances like glycerol, benzene, carbon disulfide, or glass (which range from 1.4 to 1.6). Also, the refractive index of water can change a little depending on the how hot or how cold it is, the pressure, or how much salt is in the water.
=== Chemical reactions of water ===
Water can react with some metals. It reacts with metals more reactive than hydrogen. When this happens, the metal reacts with water to make hydrogen gas and a metal hydroxide. Some metals, like the alkali metals (such as lithium, sodium, and potassium), react very strongly with water. Alkaline earth metals like calcium and magnesium react less violently. For example, sodium reacts violently and makes sodium hydroxide and hydrogen gas:
2Na + 2H2O → 2NaOH + H2
This reaction gives off a lot of heat (exothermic). It can even cause the hydrogen gas to catch fire.
Water is amphoteric. This means it can act like an acid or a base. This depends on what it is reacting with. When water is with a strong base, it gives away a hydrogen ion (H⁺) and acts like an acid. When water is with a strong acid, it takes in a hydrogen ion and acts like a base.
Water can also react with itself in a process called self-ionization:
H2O + H20 ⇌ H3O+ + OH−
This creates a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). This reaction does not happen much in water. It helps set the pH scale, which tells us how acidic or basic a liquid is.
Water can also break one molecule into two smaller ones in a process called hydrolysis. The word comes from Greek: "hydro" meaning water, and "lysis" meaning to break or unbind. In hydrolysis, one molecule breaks into two molecules. A water molecule then breaks apart into a hydrogen ion and a hydroxide ion. The hydrogen ion attaches itself to one of the two new molecules. The hydroxide ion attaches itself to the other molecule. In industry, hydrolysis is used to break down compounds like esters or salts. In biology, proteins are broken into amino acids through hydrolysis. Fats (lipids) are broken into glycerol and fatty acids. Carbohydrates, such as sucrose, are broken into simpler sugars like glucose and fructose:
C12H22O11 (sugar) + H2O → C6H12O6 (glucose) + C6H12O6 (fructose)
Hydrolysis is the opposite of a condensation reaction. Condensation combines two molecules and releases water. Hydrolysis breaks one molecule into two smaller ones by adding water.
Water can be broken down into hydrogen gas (H₂) and oxygen gas (O₂), using a process called electrolysis. In this process, an electric current is passed through water that contains small amounts of an electrolyte like sulfuric acid or salt. This helps the water conduct electricity. The electricity breaks down the water molecules:
2H2O → 2H2 + O2
Electrolysis is important because it produces clean hydrogen fuel when powered by renewable energy like solar or wind. This is often called green hydrogen. It can be used to store energy, power fuel cells, or replace fossil fuels in industry and transportation.
== On Earth ==
Hydrology is the science that studies how water moves, where it is found, and its quality all over the Earth. It is part of a larger group of sciences that study water in different places and forms:
Hydrography studies where water is located on Earth's surface.
Hydrogeology focuses on groundwater, water stored underground.
Glaciology studies ice and glaciers.
Limnology looks at inland water bodies like lakes and rivers.
Oceanography studies the oceans.
Ecohydrology explores how water interacts with ecosystems and living things.
All the water on Earth (in oceans, rivers, lakes, ice, underground, and even in the air) is called the hydrosphere. The Earth holds about 1.386 billion cubic kilometers of water. Water on Earth is not distributed equally. Most of the water on Earth is found in the oceans. About 96.5% of all the water on Earth is salt water in the oceans. This cannot used for drinking or farming. That leaves only 2.5% of the Earth's water as fresh water. Of this small percentage of freshwater, most of them are in hard to reach places. Around 68.7% of Earth's fresh water is stored in ice caps, glaciers, and permanent snow. This is mainly in Antarctica and Greenland. Another 30.1% is found as groundwater, stored in aquifers deep under the Earth's surface. This groundwater is an important source of water for wells and springs. It is very important in agriculture and for drinking. Only about 1.2% of all fresh water is water that can be found on the surface of the Earth. This includes water in lakes (about 20.9%), swamps and marshes (2.6%), and rivers (0.49%). Water can also be found in the atmosphere as vapor, clouds, and precipitation, and in soil moisture, permafrost, and living organisms. But these make up only a tiny fraction of all the water on Earth (less than 0.01%).
Fresh water is not evenly distributed across the Earth. Some places have more water than others. Countries like Canada, Brazil, and Russia have large supplies of fresh water because of lots of rivers and rainfall. In contrast, dry places like North Africa, the Middle East, and parts of Central Asia have very limited freshwater. Some tropical and temperate regions get lots of rainfall, while others may go months without much rain.
=== Water cycle ===
The water cycle (also called the hydrologic cycle) is the constant movement of water through the Earth's atmosphere and surface. Water moves between the air, ground, rivers, oceans, lakes, plants, and even underground. The main parts of the water cycle are:
Evaporation: Water from oceans, lakes, and rivers changes into vapor (gas) and rises into the air.
Transpiration: Plants release water vapor into the air through their leaves.
Condensation: Water vapor in the air turns into clouds.
Precipitation: Water vapor in the air cools, turns into liquid or solid, and falls back to Earth as rain, snow, or hail.
Runoff: Water flows across the land into rivers, lakes, and oceans.
The sun is the main source of energy that drives the water cycle. When sunlight heats up water, the water molecules move faster and can turn into vapor. This a process called evaporation. This happens in oceans, lakes, rivers, and even from the land. Plants also release water vapor through their leaves in a process called transpiration. Together, evaporation and transpiration are called evapotranspiration. The term evapotranspiration is commonly used by geologists. Water vapor is invisible to our eyes.
Winds carry water vapor in the atmosphere over long distances. When water vapor cools down, it changes back into liquid water. This is called condensation. This can happen when warm air meets cool air. The water forms tiny drops around dust or salt called condensation nuclei in the air. These drops come together to form clouds. As more droplets stick together, they grow bigger. When they get heavy enough, they fall to Earth as rain, snow, or hail. This is called precipitation.
When precipitation reaches the ground, it can do the following. It can evaporate again. It can flow over the land as runoff into rivers and lakes. Or soak into the ground to become groundwater. Water that flows in rivers and lakes is called surface water. Water that moves underground through soil and rock is called groundwater. Groundwater moves slowly and can come back to the surface through springs. It can also flow into rivers, lakes, or oceans. This shows how surface water and groundwater are connected.
Most water that evaporates from the ocean goes back to the ocean. But wind blows water vapor to land at the same rate it goes back to the ocean. Each year, about 47 trillion tons of water vapor move from the ocean to the land. About 72 trillion more tons of water vapor comes from land evaporation and plants. That adds up to 119 trillion tons of precipitation falling on land each year. Precipitation over land has many forms. Most commonly rain, snow, and hail, with some being fog and dew. Dew are small drops of water that form when warm, wet air touches a cool surface, usually in the early morning. Water droplets in the air may also refract sunlight to produce rainbows.
Water that flows over land collects in places called watersheds. They then travel through rivers, carving out valleys and deltas. These areas usually have very good soil, which is good for farming and building cities. Sometimes, too much water causes a flood. This can happen when rivers overflow or big storms push water onto the land. Other times, there is not enough water. A drought happens when a place gets very little rain for a long time. This is often because of the place or shape of the land.
=== Water and Earth's geography ===
Water plays an important role in shaping the Earth’s surface and what is happening under it. It helps form landscapes. It breaks down rocks. It even affects volcanic activity from deep under the surface. Water changes the land through both physical actions, like erosion, and chemical reactions, like breaking down minerals in rocks.
Water plays a big role in breaking down rocks on Earth’s surface. This is a process called weathering. There are two main types: physical and chemical. In physical weathering, water gets into cracks in rocks. When it freezes, it expands and makes the cracks bigger. Over time, this causes the rock to break apart. In chemical weathering, water mixes with carbon dioxide from the air or soil. This creates a weak acid called carbonic acid. Carbonic acid can dissolve some types of rock, especially limestone. When this acid gets to limestone underground, it can create large cracks, caves, and tunnels. On the surface, it can create a type of landscape called karst. Here the ground has sinkholes, caves, and holes. One amazing example of karst is the Stone Forest near Kunming, China. It has hundreds of tall, sharp towers of limestone made by water. Another example is Carlsbad Caverns in New Mexico, USA. This park has over 119 caves, all formed by water breaking down limestone. The biggest one, called the Big Room, is so large it could fit six football fields inside.
Once rocks are broken down by weathering, the pieces are moved by a process called erosion. Water moves bits of rock and minerals away. No rock is strong enough to resist weathering and erosion forever. These powerful forces have created some of Earth’s most famous landmarks. For example, the Grand Canyon in Arizona, USA, was made by the Colorado River over millions of years. The canyon is about 446 kilometers (277 miles) long, up to 29 kilometers (18 miles) wide, and about 1.6 kilometers (1 mile) deep.
Water is also very good at moving sediment. Sediment is made up of small pieces of rock, sand, and soil. Rivers, glaciers, rain, and even ocean currents move sediment over long distances. Eventually, this sediment settles in new places. Sediment is important because it adds nutrients to the soil. This helps plants grow. Places with lots of sediment, like riverbanks and deltas, are usually great for farming. They have a lot of different plants and animals. For thousands of years, the Nile River in Egypt flooded every year. This brought about 4 million metric tons of nutrient-rich sediment. Even today, the land next to the Nile is Egypt’s best farmland. Over millions of years, layers of sediment can press together to form sedimentary rocks. These rocks can contain fossils and clues about Earth’s past, like what the climate was like long ago.
Deep inside the Earth, water plays an important role in forming magma. Magma is the hot, melted rock that can lead to volcanoes. The mantle is the thick layer under the Earth's crust. It is made of solid rock even though it is hot enough to melt rocks. This is because the pressure deep inside the Earth is so strong that it stops the rock from melting. But in places called subduction zones, one of Earth's tectonic plates goes under another plate. This brings water down into the mantle. This water lowers the melting point of the rock. This means the rock can start to melt even though it is still under very high pressures. This creates magma, which can rise and cause volcanic eruptions. So, water does not just shape the land on the surface, it also helps cause big changes deep underground. Over millions of years, water has helped shape how Earth looks and behaves.
== In the Universe ==
Water is not only found on Earth. It can be found all over the universe. Astronomers have found ice, vapor, and sometimes liquid water in many places in the universe. Water ice has been found on the Moon, Mars, and comets. It has also been found on the icy moons of the outer planets, such as Europa and Enceladus. Even in interstellar space, the space between the stars, water exists as ice around tiny dust grains. It also exists as vapor in molecular clouds where new stars are born. Water has even been found in the atmospheres of exoplanets, planets outside our solar system.
A water molecule is made of two hydrogen atoms and one oxygen atom. Hydrogen came from the Big Bang. Oxygen was created inside big stars, much larger than the Sun. When these stars die and explode, they release oxygen into space. Oxygen can then combine with hydrogen to make water. Huge clouds of gas and dust, called stellar nurseries, are where new stars are born. These places often contain huge amounts of water vapor. For example, the Hubble Space Telescope found water molecules in the Helix Nebula. Water has also been found in young planetary systems around other stars. Around the star Beta Pictoris, which is about 20 million years old, scientists found water in a giant disk of gas and dust. This is likely from comets smashing into each other, asteroids, and forming planets. In the Orion Nebula, one of the biggest and most famous star-forming regions, water is still being made today. It is so large that it makes enough water every day to fill Earth’s oceans 60 times. All of this water, and the other molecules made in these star factories becomes part of new planets. On 22 July 2011, scientists found a gigantic cloud of water vapor that had 140 trillion times more water than the Earth's oceans combined around a quasar 12 billion light years from Earth. According to the researchers, the discovery shows that water has been in the universe for a very long time.
To find water in space, scientists make use of various tools and techniques. Telescopes with spectrometers can study the light coming from far away objects. Every molecule absorbs and emits light at specific wavelengths. By studying them, scientists can figure out whether there is water. Radio telescopes on the ground and space telescopes like the Hubble Space Telescope, the James Webb Space Telescope, and the Herschel Space Observatory have all helped us find water across the universe. In our own solar system, spacecraft missions have also been very important. NASA’s Galileo and Cassini missions found strong evidence of subsurface oceans on Jupiter's and Saturn’s moons. Cassini found geysers on Enceladus, with water vapor and ice particles erupting from the moon’s surface. On Mars, orbiters and rovers have found polar ice caps and certain rocks, which suggests that Mars might have had water in the past.
=== In the solar system ===
Water can be found in many places in our Solar System. Earth is the only planet we know of that has liquid water on its surface all the time. Water can be found as: solid (ice), liquid (water), and gas (water vapor) on Earth. Scientists have found tiny amounts of water vapor in the Sun’s atmosphere. The Sun is very hot. Its surface is about 5,500°C (9,932°F) and the inside is even hotter. Normally, water breaks down into hydrogen and oxygen in such heat. But there are cooler spots on the Sun, like sunspots. At sunspots, temperatures can drop to about 3,000°C (5,432°F). That is still very hot, but cool enough for water molecules to form for a short time before they break apart into hydrogen and oxygen again.
The Moon and Mercury both have water ice hidden in craters near their poles. These craters are always in the dark and never get sunlight. Because of this, the ice has stayed frozen for billions of years. NASA spacecrafts, like the Lunar Reconnaissance Orbiter and MESSENGER, have found that these ice do exist. Venus has water vapor in its atmosphere, just like Earth. But its surface is very hot and harsh. This means it does not have any liquid water on its surface. Scientists think Venus may have had water in the past, but it was lost into space. This is because Venus does not have a magnetic field to protect it like Earth does. Mars has ice caps at its poles made of water and carbon dioxide. There is also ice under the ground in many places. Rovers and orbiters have also found hydrated minerals. This means that liquid water once flowed on the surface of Mars a long time ago.
Asteroids are found near a part of the solar system called the “frost line”. This is the distance from the Sun where it is cold enough for water to freeze into ice. Beyond this line, you usually won't find liquid water because it is very cold. It can only be found hidden under ice, mixed with salt that keep it from freezing, or trapped under pressure in an atmosphere. One example is Ceres, a dwarf planet. It may have a layer of dust and rock on the outside, with salty water ice deep under the surface. Asteroids were once thought to be dry, but now scientists have found some that contain water ice or hydrated minerals. NASA’s OSIRIS-REx mission is helping us learn more about how much water some asteroids might have. Comets are pieces of ice leftover from the early solar system. They have a lot of frozen water. When a comet gets close to the Sun, the ice turns into gas, creating the famous glowing tails. There also exists a massive cloud of comets called the Oort cloud at the edge of the solar system.
The outer planets, Jupiter, Saturn, Uranus, and Neptune also have water. They are big gas giants or ice giants. They do not have a solid surface to walk on like our planet. Jupiter has water vapor in its thick atmosphere, but it is hard to see because of all the clouds. Saturn is like Jupiter. It has some water vapor in its atmosphere. Its beautiful rings are mostly made of water ice. Uranus might have an icy layer deep under its atmosphere. Neptune is similar to Uranus. Scientists think it also has an icy layer under its atmosphere that may contain water and other ices.
Some of the moons around the giant planets in our Solar System may have huge oceans of liquid water under their frozen surfaces. Europa, Ganymede, and Callisto, which orbit Jupiter, and Enceladus, and Titan, which orbit Saturn, might have underground oceans. Enceladus, a small moon of Saturn, shoots out jets of water vapor and ice from its south pole. A spacecraft named Cassini flew through these jets and found water, salts, and simple organic molecules. These are clues that there might be a hidden ocean with life. Titan, Saturn’s biggest moon, has lakes and seas on its surface, but they are filled with liquid methane and ethane, not water. Scientists think Titan has a salty water ocean deep underground, hidden under its icy surface. The moons of Uranus also have icy surfaces. Titania, the largest, has water ice and carbon dioxide ice. There might be liquid water under its surface. Triton, Neptune’s biggest moon, has a surface of frozen water ice. Deep under that ice, scientists also think it might have a liquid ocean.
The dwarf planet Pluto has a surface covered in frozen nitrogen and water ice. Pluto is extremely cold and far from the Sun. Scientists think Pluto might have a liquid ocean deep beneath its icy crust, about 100 kilometers deep. Pluto’s biggest moon, Charon, also has water ice. Beneath the surface, Charon may have had liquid water in the past. Some scientists think ice geysers might still happen on Charon.
=== In interstellar space ===
Water is not only found on planets and moons. It can also be found in the vast spaces between stars, the interstellar medium. The interstellar medium (ISM), is the scattered mix of gas, dust and radiation that can be found in the space between the stars in a galaxy. Water can be mainly found as ice covering dust grains in the interstellar medium and dense molecular clouds, where new stars are born. It can also be found as water vapor inside dense molecular clouds. In the coldest parts of the ISM, water molecules condense onto the surfaces of dust grains, forming icy mantles. These icy grains are very important ingredients in the chemistry of making stars and planets.
Molecular clouds, places where stars and planets are born, contain huge amounts of water. Water vapor has been found in many of these clouds, especially near newly forming stars. As young stars fuse hydrogen into helium they release heat around them. This warms up the surrounding ices, turning them into water vapor. This allows them to be observed by space telescopes such as the Herschel Space Observatory and the Spitzer Space Telescope. One of the most famous places where water has been studied is the Orion Nebula. Here, astronomers have found huge amounts of water vapor surrounding stars being born. In these environments, water is also very important in the chemistry that creates more complex organic molecules like amino acids. The Rho Ophiuchi cloud complex is a nearby molecular cloud about 460 light-years away. It contains protostars surrounded by water-rich ices. The ice in this region has been found using telescopes like Spitzer and JWST.
Ice and tiny grains of dust were the main ingredients that came together to form the Solar System. Scientists believe that the water in the solar system formed in space before our Sun or planets even existed. When star systems begin to form, gravity pulls together this gas and dust to make stars and planets. The dust already has water on it, which can become part of the new planets. That means planets like Earth might have been born with water already inside them.
=== On exoplanets ===
When looking for life on other planets, called exoplanets, water is one of the most important molecules scientists look for on other planets. We cannot use a telescope to look into other planets for water because they are very far away. But, astronomers have found others ways to look for water on some of these far away planets. The main way scientists study planets outside our Solar System is through something called transit spectroscopy. This means watching a planet as it passes in front of its star. When it does, some of the star’s light goes through the planet’s atmosphere to us. Depending on what the atmosphere is made of, certain parts of the light get blocked or bent. This creates a kind of “fingerprint” in the light that scientists can study. By looking closely, they can figure out which gases are in the atmosphere, like water or methane. Right now, studying the atmospheres of exoplanets is still very hard. Our tools are not perfect for this yet and it takes very careful measurements.
This method has found water vapor on many "hot Jupiters", such as HD 189733 b and HD 209458 b. These are large gas giants very close to their stars. Though these planets are far too hot for liquid water. Water exists as water vapor in the atmospheres of these planets. In recent years, telescopes have begun finding signs of water on smaller planets, especially sub-Neptunes and super-Earths. These are planets smaller than gas giants but larger than the Earth. One example is K2-18b, a super-Earth found by NASA's Kepler spacecraft in 2015. It is a planet with eight times the mass of the Earth that orbits a so called red dwarf star, which is much cooler than the sun. K2-18b can be found in the “habitable zone” of its star. This means it has the right temperature to have liquid water. Given its mass and radius, K2-18 b may either be a rocky planet with a thick atmosphere or be more like Neptune. Observations with Hubble and the James Webb Space Telescope (JWST) have found water vapor in its atmosphere. Though scientists cannot say if it has clouds, oceans, or even rain. Planets in the habitable zone, are places scientists are looking with new technology like the James Webb Space Telescope.
=== The search for extraterrestrial life ===
When scientists look for life in space, they often start by looking for water. Every living thing on Earth needs water to survive. Water has special chemical properties that make it perfect for life. It is really good at dissolving other substances, which helps living things carry out chemical reactions. Water stays liquid over a wide range of temperatures. It can help keep living organisms from getting too hot or cold. It also helps move nutrients and waste in and out of cells and living organisms. That is why scientists often say “follow the water” when searching for life beyond Earth.
Scientists think moons like Europa (which orbits Jupiter) and Enceladus (which orbits Saturn) might be able to have life. Both moons have thick layers of ice on their surface. Under that ice, scientists believe there are massive oceans of liquid water. The bottom of these oceans could be like hydrothermal environments found in the deep sea on Earth. On our planet, hydrothermal vents release hot, mineral-rich water from under the seabed. This creates a place where life thrives without sunlight. Instead of using sunlight for energy (like plants do), the organisms living there use chemical energy from the minerals in the water. This is a process called chemosynthesis. If similar hydrothermal vents exist on Europa or Enceladus, they could provide the energy and nutrients needed for life to survive in complete darkness, just like Earth’s deep sea life. Scientists have already found clues supporting these ideas. On Enceladus, for example, NASA’s Cassini spacecraft found jets of water vapor, ice particles, and organic molecules shooting out from cracks from the moon. This is a strong sign that there is liquid water and hydrothermal vents under its icy surface. These discoveries make Europa and Enceladus key targets for future space missions.
Mars remains a key target in the search for life beyond Earth. Although the planet is cold and dry today, it shows strong signs that it might have had water in the past. Ancient river valleys, dry lake beds, and minerals that only form in water suggest that liquid water once flowed on the Martian surface. Scientists believe that billions of years ago, Mars may have had a thicker atmosphere and a milder climate, possibly making it a habitable world. Even now, there may be salty liquid water hidden underground, especially near the poles or beneath the surface. Briny water, which contains dissolved salts, can stay liquid at colder temperatures, increasing the chances that it might still exist on Mars. To explore this possibility, NASA and other space agencies have sent robotic missions like the Perseverance and Curiosity rovers to study Mars up close. These rovers have advanced tools to analyze rocks, soil, and even the atmosphere. They are looking for biosignatures, which are chemical or physical signs that could suggest past life.
Scientists often look for water when they search for life on exoplanets. And they often look for planets in the habitable zone. This is the area around a star where temperatures are just right for liquid water to exist on a planet. If a planet is too close to its star, it will be too hot and water will boil away. If it is too far, it will be too cold and water will freeze. But in the habitable zone, things can be just right for water to stay liquid. Earth can be found in the habitable zone of the Sun. This is one reason it has oceans, rivers, and rain. That is why it can support so many kinds of life. When scientists study planets around other stars (called exoplanets), they look to see if those planets are also in the habitable zone. If they are, and they have the right kind of atmosphere, they might have water. And, they might even have life. Beyond our solar system, astronomers have discovered water vapor in the atmospheres of some exoplanets. These findings suggest that water, a key ingredient for life as we know it, might be common in the universe. This ongoing research brings us closer to answering one of the biggest questions in science: Are we alone in the universe?
== Uses of water ==
Plants and animals (including people) are mostly water inside, and must drink water to live. It gives a medium for chemical reactions to take place, and is the main part of blood. It keeps the body temperature the same by sweating from the skin. Water helps blood carry nutrients from the stomach to all parts of the body to keep the body alive. Water also helps the blood carry oxygen from the lungs to the body. Saliva, which helps animals and people digest food, is mostly water. Water helps make urine. Urine helps remove bad chemicals from the body. The human body is between 60% and 70% water, but this value differs with age; i.e. a foetus is 95% water inside.
Water is the main component of drinks like milk, juice, and wine. Each type of drink also has other things that add flavor or nutrients, things like sugar, fruit, and sometimes alcohol. Water that a person can drink is called "potable water" (or "drinking water"). The water in oceans is salt water, but lakes and rivers usually have unsalted water. Only about 3% of all the water on earth is fresh water. The rest is salt water.
Many places, including cities and deserts, don't have as much water as people want. They build aqueducts to bring water there.
Though people can survive a few months without food, they can only survive for a day or two without water. A few desert animals can get enough water from their food, but the others must drink.
Water has no smell, taste, or color.
Water is also used for recreational purposes, see list of water sports.
Water is used as both the coolant and the neutron moderator in most nuclear reactors. This may be ordinary water (called light water in the nuclear industry) or heavy water.
Water is also used for washing a lot of objects. Goods, services and people are transported to other countries in watercrafts on bodies of water.
Water is used in chemical reactions as a solvent or reactant. Water is also used in fire fighting. Water is also used for cooking.
== Water laws, crisis, and geopolitics ==
=== Water laws ===
Water laws are rules that help decide how water is shared, used, and protected. These laws are important because water is something that everyone needs. People, farms, businesses, and nature all depend on water. Water laws help figure out who can use water, how much they can use, and what they can use it for. They also try to make sure that water is used fairly and not wasted or polluted. In many places, water is limited, and if it is not managed well, it can run out or get too dirty to use. Water laws are meant to stop problems like this including fights over water. They also help make sure there is enough clean water for things like drinking, growing food, making energy, and protecting the environment.
Water rights are the rules about who can use water and how much they can use. These rules are part of water laws. There are different kinds of water rights depending on where you live and the laws people follow. One common system is called riparian rights, which is often used in places with plenty of water. With riparian rights, if you own land next to a river, lake, or stream, you have the right to use the water. But you have to be careful not to harm the people who live downstream. In drier places, they often use a different system called prior appropriation. This follows the rule of "first in time, first in right." The first person to take water for a useful purpose has the right to keep using it, even if their land is not next to the water. In many parts of the world, especially in rural or indigenous communities, customary or traditional laws also guide how water is shared. These laws are based on old practices and cultural values that help people respect and protect water. Different countries have their own laws and rules for managing water. Some countries focus on deciding who can use water and how they can use it, while others pay more attention to stopping pollution or building things like dams and pipelines to help control water. When rivers, lakes, or underground water cross borders between countries, water law becomes more complicated. In these cases, countries need to work together and make agreements to share the water fairly and avoid fights. For example, many countries share big rivers like the Nile, Mekong, and Danube. These countries cooperate through special agreements to manage the water in a way that works for everyone.
Water use is usually managed by national or local governments and special government agencies. These groups decide how much water people can use, check that the water is clean and safe, and protect the plants and animals that need water to live. They also help solve problems when two communities or businesses want to use the same water source. Water governance means making sure water systems are cared for, pollution is controlled. It also means making sure everyone has access to clean water for drinking and hygiene. Good water management is very important to handle problems like droughts, floods, growing populations, and climate change. There are many important examples of water laws and how they affect people. In the United States, the Clean Water Act is a big law that helps protect rivers, lakes, and other water from pollution. In Africa, the countries along the Nile River have talked and sometimes argued for a long time about how to share the river’s water fairly. Some countries are starting to say that water is a public good or even a human right. This means that everyone should be able to get clean water, no matter how much money they have or who they are.
=== Water crisis ===
A water crisis is a serious situation that happens when people do not have enough clean and safe water to meet their daily needs for drinking, cooking, washing, and farming. It also includes times when water is available but too polluted or too far away to be used safely. A water crisis can also affect the environment. It can harm rivers, lakes, and plants and animals that depend on water. This problem is not just about having no water at all. It also includes having water that is too dirty, too expensive, or too difficult to reach. There are many reasons why water crises happen.
One major cause is population growth. As more people are born and the world’s population grows, more clean water is needed for drinking, cooking, washing, and growing food. As cities get bigger and more people use water, rivers, lakes, and underground water sources are being used up faster than nature can replace it. This causes a water scarcity, which means there is not enough clean water for everyone’s needs. In big cities, the problem can get worse. When lots of people live close together, they all need water at the same time. In poor neighborhoods or fast-growing areas, some people may not have any clean running water at all. In the countryside, farmers use a lot of water to grow crops and feed animals. As the population grows, the demand for food grows too, so farmers need even more water. Some use strong pumps to pull water from underground, but if they take too much, the water underground can run out.
Another big problem is pollution. Even though there is water in rivers, lakes, and oceans, a lot of it is not safe to drink or use because it is polluted. Pollution happens when harmful things like chemicals, trash, or dirty water from homes and factories get into natural water sources. This makes the water dangerous for people, animals, and plants. One major source of pollution is waste from homes and cities. When people wash dishes, take showers, or flush toilets, that dirty water has to go somewhere. In some cities, it goes to special treatment plants that clean the water. But in many places around the world, there are no good systems, so the dirty water goes straight into rivers or lakes. This can carry germs that cause serious diseases like cholera or diarrhea. Even in big cities, if the water system breaks or gets too full during a storm, dirty water can mix with clean water and make it unsafe to drink. Factories and farms also cause a lot of water pollution. Some factories dump leftover chemicals, oil, or heavy metals into nearby rivers to save money. These dangerous substances poison the water and can build up in fish, making them unsafe to eat. On farms, people use fertilizers and pesticides to help crops grow and kill bugs. But when it rains, these chemicals can wash off the land into rivers or lakes. This is called “water runoff.” It can make algae grow too fast. When the algae die, they use up the oxygen in the water. Then fish and other animals cannot survive, and parts of the water become “dead zones” where nothing can live. Plastic is another big problem. Every year, tons of plastic bottles, bags, and wrappers end up in rivers and oceans. Plastic does not break down easily, so it can float in the water for years. Sea animals like turtles or fish might eat plastic by mistake and die. Tiny pieces of plastic, called microplastics, have even been found in drinking water and seafood. Scientists are still studying how these microplastics might affect human health.
Another big reason for water problems is overuse. This means people are using too much water too fast, much faster than nature can refill it. Every day, water is needed for many things like drinking, cooking, cleaning, farming, making clothes, building houses, and running factories. As more people live on Earth, they use more water. But there is only a limited amount of fresh water on the planet. When we take too much water without giving nature enough time to replace it, rivers dry up, lakes get smaller, and underground water sources called aquifers drop lower and lower. Farming uses the most water of all. Farmers need water to grow crops and take care of animals, but in many places, they use more water than necessary. Sometimes they flood their fields, and a lot of the water is wasted or lost to evaporation. In dry places, farmers often pump water from deep underground. At first, this works well, but if they keep pumping too much, those underground water supplies start to run out. Once an aquifer is empty, it can take many years or even centuries to fill up again. This is happening in parts of the United States, India, China, and many other countries. Factories and industries also use huge amounts of water to make things like paper, steel, clothes, and electronics. For example, it takes thousands of liters of water to make just one pair of jeans or a hamburger.
Another big reason for the water crisis is poor infrastructure. Infrastructure means the systems and buildings we use to carry, store, clean, and deliver water, like pipes, pumps, water treatment plants, and storage tanks. In many places, especially in poorer countries or old cities, these systems are old, broken, or not built well. This means that even if there is enough water nearby, people still cannot get clean, safe water in their homes. Because of this, millions of people either get no water at all or have to use water that can make them sick. In some poor or rural areas, there might be no water system at all, so people have to walk long distances to rivers or wells to get water by hand. Sometimes this water is not clean because there is no way to filter or clean it. In cities, even when pipes and pumps exist, they may be old and not well cared for. Leaking pipes waste a lot of water, sometimes up to half of it is lost before it even gets to homes or schools. In crowded neighborhoods, especially slums, water pipes may only work a few hours a day or not at all. People there have to buy water from trucks or use unsafe sources. Water treatment plants are supposed to clean the water by removing dirt, germs, and chemicals before people drink it. But if these plants are too small, do not have enough money, or are broken, the water from taps can still be unsafe. Dirty water can cause diseases like cholera, typhoid, and diarrhea, which kill thousands of people every year, especially children. Sometimes, clean water and dirty sewage use the same underground pipes. When those pipes break or flood, the two can mix, making people sick without them knowing. As more people move to cities, they need more water, but water systems do not always grow fast enough to keep up. During heat waves or droughts, the systems can break down even more. And during floods, water pipes may burst or get clogged, leaving people without water for days.
Another big reason the world has a water crisis is that governments often do not manage water well. Even if a country has enough water, bad planning, weak laws, and unfair choices can cause big problems. In many places, water is not shared fairly. Some people, especially those in rich neighborhoods or powerful companies, get plenty of clean water, while others in poor areas get very little or none at all. Sometimes governments build big water projects like dams or canals, but these only help a few people and leave out whole communities. Poor water planning also causes waste and shortages. In some countries, water is used without limits. Big farms or factories take as much water as they want from rivers or underground, and the government does not keep track of it. This causes overuse, where water is taken faster than nature can replace it. Also, water bills may be too cheap or not collected at all, so people do not try to save water. In other places, governments do not spend enough money on water systems, so pipes leak, treatment plants break, and many areas have no working water services. Sometimes, powerful people or companies bribe officials to get more water than they need, while others are ignored. Governments may promise to build water projects but never finish them, or the money disappears because of corruption. Sometimes leaders make decisions without asking local people what they really need, so water projects do not fix real problems. For example, a city might build a big water pipeline but forget to build toilets or drains, which can cause health problems. Another issue is that many governments do not plan for the future. As cities grow and the climate changes, water needs change too. But without good planning, old water systems cannot keep up. When droughts happen, there are no backup plans. When floods come, water systems break down.
At the same time, climate change is making the water problem worse. As the Earth gets hotter, it changes how water moves in nature. Normally, water falls as rain or snow, flows into rivers and lakes, and then evaporates back into the air. But with climate change, this natural water cycle gets out of balance. In many places, rain does not come when it is needed, or it falls all at once in heavy storms that cause floods. Some areas are getting drier, while others get too much water. This makes it harder for people to get clean and steady water when they really need it. In dry places, climate change causes droughts to happen more often and last longer. A drought is when there is very little rain for a long time. This causes rivers to shrink and lakes to dry up. Crops would not grow, and animals would not have enough water to drink. Farmers suffer the most because they need water to grow food and take care of their families. On the other hand, some places get too much water at once. Heavy rain from warmer temperatures can cause floods that destroy homes, farms, and water systems. Flood water can mix with sewage and chemicals, making it dirty and unsafe to drink. Even though floods bring lots of water, it is often not clean or useful. Also, glaciers and snowpacks in mountains are melting faster than before. These usually act like natural water tanks, slowly releasing water during dry months. But now, they are disappearing, which means millions of people who live downstream will have less water in the future.
The world is facing a very serious water crisis, and the numbers show how big the problem really is. Right now, more than 2.2 billion people, almost 1 out of every 4 people on Earth, do not have safe drinking water at home. That means they cannot just turn on a tap to get clean water to drink, cook, or wash with. Even more people, about 3.5 billion, do not have proper sanitation, like toilets or safe ways to get rid of dirty water. Without clean water and safe toilets, diseases spread easily, and many children, especially in poor areas, get sick. According to the World Health Organization, around 500,000 people die every year from diseases caused by dirty water and poor hygiene. About 4 billion people, more than half the world’s population, face serious water shortages for at least one month every year. Some of the countries with the worst water problems include India, Egypt, Iran, and parts of the United States, like California. In these places, rivers are drying up, underground water is running low, and lakes are shrinking. For example, the Aral Sea, which used to be one of the largest lakes in the world, has almost completely dried up because people used too much of its water. In Cape Town, South Africa, the city almost ran out of water in 2018. The crisis was so bad they called it “Day Zero,” the day the taps would be turned off if water ran out. Climate change is making things worse. As the planet gets hotter, droughts are happening more often and lasting longer. Rain patterns are changing, so some places get too much rain all at once, causing floods, while other places don't get enough rain, leading to dry land and crop failures. The United Nations says that by 2050, over 4 billion people might not have safe water at home unless we make big changes. Even in places that have enough water, the systems that deliver it do not always work well. The World Bank says the world loses about $260 billion every year because of bad water systems, like leaking pipes, poor planning, or people getting sick and missing work or school because of waterborne diseases. At the same time, people living in slums or rural areas often have to pay more money per liter for water than rich people in cities. That is because they have to buy it from private sellers or carry it from far away. This is unfair and keeps many families stuck in poverty.
There are many ways we can fix the water crisis, but it takes everyone working together, including governments, businesses, communities, and ordinary people. One of the most important steps is to build and fix water systems. This means making sure pipes, pumps, treatment plants, and tanks work well and bring clean water to everyone who needs it. In many poor places, there are no water systems at all, so people have to walk far to get water. By investing in strong water systems, clean water can be delivered straight to homes, schools, and hospitals. Good systems also stop leaks, so less water is wasted before it even reaches people. Another important solution is to use water more carefully and waste less. Many people and factories use more water than they really need. Simple things like fixing dripping taps, taking shorter showers, and turning off the water while brushing your teeth can save a lot of water. Farmers, who use most of the world’s water, can use better methods like drip irrigation and collecting rainwater to grow crops with less water. In cities, recycling water from sinks and showers to flush toilets or water plants helps save even more. Protecting and cleaning our water sources is also very important. Rivers, lakes, and underground water can get polluted by trash, chemicals, and sewage. To keep water clean, we need to stop dumping waste into nature. Governments should make strong laws to control pollution from factories and farms. People can help too by not throwing garbage into rivers or drains, and by using less plastic and fewer harmful cleaning products. Fair government rules are needed as well. In some places, water is not shared fairly. Rich neighborhoods and big companies get plenty of water, while poor communities get very little. Governments must treat water as a basic human right, not just something to buy and sell. They should plan for the future by knowing how much water is available, who needs it most, and how to protect it from climate change. They should also include local people when making decisions about water use and sharing. Education is another important part of solving the water crisis. Many people do not know how serious the problem is or what they can do to help. Schools, TV shows, and community projects can teach kids and adults about water and why it's important to save it. Finally, technology can help a lot. New tools like water filters, low-water toilets, smart irrigation systems, and apps that track water use make saving water easier. Even simple tools like tanks that collect rainwater from rooftops can give families clean water in dry areas. Scientists and engineers are working on ways to clean salty ocean water, safely recycle wastewater, and watch water use from space. All these ideas together can help make sure there is enough clean water for everyone.
=== Water geopolitics ===
Water is one of the most important resources on Earth. People need it to drink, cook, clean, and grow food. But when there is not enough water, or when it is not shared fairly, it can lead to conflict between people, groups, or even countries. One major cause of water conflict is scarcity. Scarcity means there is not enough water for everyone who needs it. This can happen in dry places where it does not rain much, or in areas where the population is growing quickly and using too much water. When water is limited, people may start to argue or fight over who gets to use it. For example, if two farmers both use the same river to water their crops, but the river starts to dry up, they may blame each other and argue about who should get more water. These kinds of problems can happen between neighborhoods, cities, or even whole countries that share rivers or lakes.
Another reason people fight over water is when rivers or lakes cross borders between countries. These are called transboundary water sources, and they can cause serious problems. For example, the Nile River flows through several countries in Africa. Each country wants to use the water for things like farming and electricity. If one country builds a dam or takes more water than before, the others may get upset or worried they would not have enough. The same kind of conflict happens in other parts of the world. India and Pakistan have had disagreements over the Indus River, and countries in Central Asia have argued over rivers that come from melting mountain glaciers. If countries do not find fair ways to share the water, it can lead to political fights and even war. Pollution is another cause of water conflict. When factories, farms, or cities dump waste into rivers or lakes, the water becomes dirty and unsafe. If one group pollutes the water and another group depends on it for drinking or farming, big problems can happen. People downstream may get sick or lose their crops and blame those upstream. This can lead to lawsuits, protests, or even violence. Even within one country, different areas or groups might argue about who is polluting the water and who should pay to clean it up. These fights can make it even harder to solve the water crisis.
Unfair sharing of water can also cause problems. In many places, rich neighborhoods or big companies get more water than poor communities. When there is not enough water for everyone, and some people have plenty while others have none, it can make people upset and angry. This can lead to protests or even fights. For example, in some cities, poor areas called slums may have no running water at all. But at the same time, fancy hotels nearby might use a lot of water to fill swimming pools or run fountains. When people see this kind of unfairness, they may feel they are being treated badly and demand change. Climate change is also making water conflicts worse. As the Earth gets hotter and rain becomes less regular, droughts are happening more often. This puts more stress on water supplies and makes people compete even more. In some places, climate change is melting glaciers and drying up rivers. When water becomes harder to find, people worry more and fight harder over the little that is left. If governments do not step in to share water fairly and plan for the future, these conflicts could become more serious over time.
One of the most well-known water conflicts in the world is happening along the Nile River in Africa. The Nile is the longest river in the world, and it flows through 11 different countries, including Ethiopia, Sudan, South Sudan, Egypt, and Uganda. This river is very important because millions of people use it every day for drinking water, farming, fishing, and making electricity. But since so many countries share the Nile, there are many disagreements about how the water should be divided. The biggest conflict is between Ethiopia, Sudan, and Egypt. Each country depends on the Nile for different reasons, and they do not always agree on what is fair. A major reason for the conflict is a huge dam that Ethiopia is building. It is called the Grand Ethiopian Renaissance Dam, or GERD. Ethiopia started building this dam in 2011 on the Blue Nile, one of the two main branches of the Nile River. Ethiopia says the dam is important because it will create electricity for millions of people who do not have enough power. They believe it will help the country grow and develop. However, Egypt is very worried about the dam. Egypt gets about 90% of its water from the Nile, and it fears the dam will lower the amount of water flowing to its farms and cities. Egypt needs the Nile for almost everything, especially to grow crops in the desert. Sudan is in the middle. On one hand, the dam could help Sudan by reducing floods and giving them more electricity. On the other hand, Sudan is worried that Ethiopia might fill the dam too quickly, which could reduce the amount of water Sudan receives for farming and drinking. Sudan wants all three countries to make a clear agreement so that everyone can benefit and no one gets harmed. Ethiopia, Egypt, and Sudan have been talking about this issue for many years, but they still have not made a final deal. Egypt wants strict rules about how and when Ethiopia can fill the dam, especially during dry years. Ethiopia wants to control the dam itself and believes it has the right to use the river that starts in its land. Because of these disagreements, there have been many arguments, tense meetings, and even threats. Some people worry that if the countries cannot work together, it could lead to a serious crisis or even conflict.
Another example of water conflict is between India and Pakistan. These two countries have not always gotten along, and sharing water has made things even more difficult. The Indus River and its smaller rivers start in India but flow into Pakistan. In 1960, the two countries signed a water treaty to divide the rivers fairly. But even today, each country is worried that the other might take more water than they should. When India builds new dams or water projects, Pakistan gets alarmed and accuses India of breaking the agreement. These water issues add to the already tense relationship between the two countries. In the Middle East, water is very limited, and this leads to many conflicts. One example is the Jordan River, which flows through Israel, Jordan, and Palestine. All three groups need the river for drinking water, farming, and everyday life. But over the years, the river has shrunk because of overuse and pollution. As the water supply drops, arguments have grown. In the West Bank, many Palestinian communities struggle to get enough water, while nearby Israeli settlements often have steady supplies. This unfair access makes people angry and adds to the political tension. Some efforts have been made to share the water more fairly, but it is hard because the groups do not trust each other. In Yemen, a country dealing with war and poverty, water shortages have also led to conflict. Many people there do not have clean water. As wells dry up, villages and tribes sometimes fight over who gets to use the last water sources. In some rural areas, armed groups have taken control of water supplies, making it even harder for families to get the water they need. Some experts believe that water problems have made Yemen’s civil war even worse. This shows how lack of water can become even more dangerous when a country is already in crisis.
In the United States, water conflicts happen more often than people might think, especially in the western part of the country where water is harder to find. One of the biggest and most well-known water fights is over the Colorado River. This river flows through seven states: Colorado, Wyoming, Utah, New Mexico, Arizona, Nevada, and California. It also flows into Mexico. More than 40 million people use the Colorado River for drinking water, farming, and making electricity. But lately, the river has been shrinking because of drought, climate change, and using too much water. The states argue over how much water each one should get. For example, California uses a lot of water for growing food in the desert, while big cities like Las Vegas and Phoenix need more water as more people move there. The government has tried to help the states make fair deals, but it’s been very hard to agree on a long-term solution. Another big water conflict in the U.S. is between Georgia, Alabama, and Florida. This fight has been going on for decades. These states share rivers like the Chattahoochee and the Flint, which come together to form the Apalachicola River. Georgia wants more water for the city of Atlanta and for farms. But Alabama and Florida say that if Georgia takes too much water, there would not be enough left for them. Florida especially needs the water to keep its seafood industry alive in Apalachicola Bay. This fight has gone all the way to the U.S. Supreme Court, but even after many years, it is still not solved. Even in places with more water, like around the Great Lakes, there can still be conflicts. Some towns and companies want to take more water out of the lakes for their own use, but others worry this could hurt the environment or lower the water levels. The Great Lakes are shared by several U.S. states and Canada, so any plan to use the water has to be agreed on by everyone. In 2008, a deal called the Great Lakes Compact was made to protect the lakes and stop people from taking water unfairly. Still, some places try to find ways around the rules, which causes more arguments and concern.
Even though water can sometimes cause conflict, it can also help bring people together. Many countries, states, and communities have worked hard to cooperate and make fair deals about how to share water. These water agreements are very important because they help prevent arguments, protect nature, and make sure everyone has the water they need. When countries share rivers, lakes, or underground water, they often create treaties, or written agreements. These treaties explain how much water each side can use and what to do if there is a problem. They might also include plans to keep the water clean and to stop pollution and waste. One famous example is the Indus Waters Treaty between India and Pakistan. This treaty was signed in 1960 with help from the World Bank. The Indus River system flows through both countries and is very important for farming and daily life. Even though India and Pakistan have had many political problems and even wars, this water treaty has mostly worked well. It divides the rivers between the two countries and includes rules about building dams and using the water fairly. The treaty has helped stop big water fights for over 60 years. This shows that even countries that do not get along can work together when it comes to water.
Another important example of water cooperation is the Senegal River Basin agreement in West Africa. The Senegal River flows through several countries, including Senegal, Mali, and Mauritania. In 1972, these countries created a group called the Organisation for the Development of the Senegal River (OMVS). They agreed to manage the river together, share the water fairly, and build dams and power plants that help all the countries. The group listens to farmers, fishermen, and local leaders to make sure everyone’s needs are heard. This kind of teamwork helps people trust each other and solve problems peacefully. In Europe, there are many rivers that cross between countries. One of the most important is the Danube River, which flows through more than 10 countries. In 1994, these countries signed the Danube River Protection Convention. They promised to work together to keep the river clean, prevent floods, and protect the plants and animals that live in and around the water. The agreement includes regular meetings, water testing, and teamwork during emergencies. Because of this, the Danube remains safe and helpful for millions of people. The United Nations (UN) also supports water cooperation around the world. In 1997, the UN created a special agreement called the Convention on the Law of the Non-Navigational Uses of International Watercourses. This set of rules encourages countries to share water fairly, avoid harming each other, and settle arguments peacefully. Not all countries have signed it, but it still helps guide how nations work together to manage shared rivers and lakes. The UN also celebrates World Water Day every year on March 22 to remind everyone how important it is to work together on water issues.
== In culture ==
=== In religion ===
Water has deep meaning in many cultures and religions around the world. Almost everywhere, water is seen as a symbol of purity, life, and change. It often stands for cleansing, not just of the body but also of the spirit. People believe water can wash away bad things and help start fresh. It is important to many religious beliefs and spiritual practices. It can represent the cycle of life, rebirth, and the connection between the physical world and something sacred or divine. In many faiths, water is used in religious rituals to bless or purify people. These ceremonies include baptisms, ritual washings, and blessings. For example, people may wash their hands, face, or whole body before prayer or entering a sacred place to show respect and prepare for spiritual contact. In baptism, a person is dipped in or sprinkled with water to mark the start of a spiritual journey. It often means the washing away of sins and beginning a new life. Water may also be sprinkled or offered during other ceremonies to bless people, objects, or spaces. These practices show the belief that water has spiritual power.
Different religions use water in special ways. In Christianity, baptism is an important ceremony where water is used to show spiritual cleansing and a new life in Jesus Christ. In Islam, water is used in wudu (a small washing) and ghusl (a full-body washing). These are done before prayers and other holy activities to be clean in body and spirit. In Hinduism, water is very sacred, especially rivers like the Ganges. People believe this river can wash away sins. It is used in many ceremonies, including funerals. Buddhists use water in temple rituals as a sign of offering and for spiritual cleansing. In Judaism, there is a special bath called a mikveh. People use it for purification during important times, like before getting married or when entering the religion. In Sikhism, being clean is part of being spiritual. Sikhs use water for bathing and in some religious rituals. Many indigenous and animist traditions also see water as sacred. Rivers, lakes, and springs are believed to be the homes of spirits or gods. They are often part of rituals and traditional stories.
Sacred water sources are very important in many religions. People often travel long distances to visit these special places during pilgrimages. These water sites are believed to have healing powers or a spiritual presence. For example, in Christianity, many people visit the spring at Lourdes in France, which is believed to heal the sick. Every year, millions of people go there to pray and collect water. In Hinduism, the Ganges River is one of the most holy rivers. Bathing in it is believed to wash away sins and bring blessings. In Islam, the Zamzam Well in Mecca is a sacred part of the Hajj pilgrimage. It has deep spiritual and historical meaning for Muslims.
=== In philosophy ===
In ancient times, people believed that everything in the world was made from a few basic things called elements. One of the first known Western philosophers, Thales of Miletus, lived in the 6th century BCE and thought that water was the most important of them all. Thales believed that water was the origin of everything. He called it the "archê," a Greek word that means "first principle" or "beginning." He noticed that water is essential for life and can exist in three forms: solid, liquid, and gas. Because of this, he thought water was the basic building block of the universe. Thales was one of the first people to try to understand the world through observation and reason, instead of relying on myths or stories. His ideas helped start what we now call natural philosophy, the early form of science.
As philosophy grew in different parts of the world, many cultures gave water an important place in their way of thinking. In ancient Greece, famous philosophers like Plato and Aristotle believed that everything was made of four main elements: earth, air, fire, and water. Each element had special qualities. Water was thought to be cold and wet. It was linked to change and movement because of the way it flows. In Eastern philosophy, water also had deep meaning. In Daoism, a major tradition from China, water is a symbol of ideal behavior. It flows gently, adapts to its surroundings, and can slowly wear down even hard rock, not by force, but with patience and persistence. This idea is part of the Daoist teaching called wu wei, which means acting without effort or force. In Indian philosophy, water is one of the Pancha Mahabhuta, or five great elements, in both Hinduism and Buddhism. Water stands for emotion, cleansing, and flow. It is seen as important not just for the body, but also for the soul and the balance of nature.
Throughout history, philosophers have used water as a symbol or metaphor in their writing. Water is often used to represent the flow of time, the way we think and feel, or how things can change shape while staying as the same substance. In many traditions, water stands for change or transformation. It can turn into ice or steam, then go back to being liquid again. Because of this, philosophers use water to talk about how life is always changing, and how nothing stays the same forever. Water is also used to explain how our identity (who we are) is not fixed. Like water takes the shape of whatever container it is in, people can be shaped by their surroundings and experiences. In more recent times, philosophers still talk about water in many important ways. In ecological philosophy, they explore how people are connected to nature and the environment, and water is a big part of that. In existentialism, water can be a symbol for things like uncertainty, deep thoughts, or the search for meaning in life. In environmental ethics, water is often discussed in debates about natural rights, fairness, and how to protect the planet. Some modern philosophers believe that water should be seen not just as a resource we use, but as a living system that should be treated with respect and care. Others study how water affects people’s lives, culture, and identity. In a type of philosophy called phenomenology, which looks at how we experience the world, water might be studied through the senses. How it feels, looks, sounds, and moves.
=== In folklore ===
Water has been connected to mythical creatures and spirits in many cultures around the world. Stories often tell of beings like mermaids, nymphs, kelpies, nāgas, and other water spirits that live in rivers, lakes, or the ocean. These magical beings are sometimes seen as protectors of water. They might guard a water source and punish people who harm it. In other stories, they may try to trick or lure humans into the water. Some water spirits are wise and kind, offering help or magical advice. Others are tricksters or bring bad luck. In Japanese folklore, there is a creature called the kappa. Kappa are often seen as water spirits or kami in Japanese folklore. They can act in both mischievous and dangerous ways. Sometimes, they play pranks, like trying to peek under people's clothing near the water. But in other stories, they can be harmful, even trying to drown people or animals or scare children. Even though they can be scary, not all kappa are mean. Some are shown to be friendly and can even help humans. In Celtic legends, water fairies are magical beings that live in rivers, lakes, springs, and wells. They are often connected to nature. They are believed to guard the water and its power. These fairies can be kind and helpful, but they can also be tricky or dangerous if they are disrespected. In parts of Africa, people believe in Mami Wata, a powerful water spirit who can appear as a beautiful woman or a mermaid. She is seen as a guardian of rivers and oceans. Mami Wata protects the natural world. She can bring blessings to those who honor her. But if someone disrespects her, pollutes the water, or breaks a promise, she may punish them. In Greek mythology, sirens were dangerous creatures who lived on rocky islands in the sea. They looked like part woman and part bird, but later stories showed them to be more like mermaids. Sirens had beautiful voices and sang songs so sweet that sailors could not resist. The music would lure the sailors closer and closer until their ships crashed on the rocks.
In many myths and folktales, water is seen as a gateway or border between different worlds. Rivers, lakes, and oceans are often shown as dividing lines between the world of the living and the dead, or between the human world and the spirit world. In Greek mythology, there is a river called the Styx that separates the world of the living from the underworld. When someone dies, their soul must cross the river to reach the land of the dead. A boatman named Charon ferries the souls across, but only if they have a coin to pay him. In Celtic stories, lakes and misty waters are often seen as gateways to the Otherworld, a magical realm where spirits and fairies live. Some tales say that if you walk into the mist on a quiet lake, you might disappear into another world. The boundary between the worlds is thin near water, especially at dawn or dusk. In Japanese folklore, there is a belief that spirits of the dead must cross a river called the Sanzu River to reach the afterlife. Like the Greek Styx, it is a border between the living and the dead. Depending on how someone lived their life, they might cross on a bridge, wade through shallow water, or struggle through deep, rough currents. In some Native American traditions, water is a pathway between the physical world and the spirit world. Shamans or spiritual leaders may enter a trance near a river or waterfall to connect with spirits.
In many cultures, water plays an important role in myths about creation and destruction. In Babylonian mythology, the world began from a vast, dark ocean. Two great water beings, Apsu (fresh water) and Tiamat (salt water), came together to create the first gods. Later, Tiamat became angry and turned into a monster to destroy them. One of the gods, Marduk, defeated her and used her body to form the sky and the earth. In the Bible, there is the story of Noah's Ark, where God sends a great flood to destroy the world because of human wickedness. The floodwaters cover the earth, wiping out nearly everything. But after the water goes down, life begins again. In Hindu mythology, the god Vishnu rests on a cosmic ocean before the world is created. From his navel grows a lotus flower, and from that flower comes Brahma, the creator god. Later, when the world becomes evil, Vishnu sends great floods to destroy it and prepare for a new age. In Norse mythology, at the end of the world, called Ragnarök, giant waves and floods cover the earth as the sea serpent Jörmungandr rises from the ocean. Many gods die, and the world is destroyed in water and fire. But after the flood, the world slowly rises again, green and peaceful, ready for a new beginning.
In many myths and legends, water is linked to healing and change. People have long believed that special places like sacred springs, wells, and fountains have magical or healing powers. In these stories, someone who drinks the water or bathes in it might be cured of an illness, feel stronger, or even gain special abilities. In Celtic folklore, there are many stories about sacred wells and springs. These places were believed to be blessed by spirits or ancient gods. People would visit them to wash their wounds or drink the water, hoping to be healed. Some wells were also believed to grant visions or wisdom if the visitor was pure of heart. In Christian tradition, the waters of Lourdes in France are said to have healing powers. A young girl named Bernadette saw visions of the Virgin Mary near a spring. Since then, millions of people have traveled to Lourdes to bathe in the water or collect it, praying for cures to sickness or pain. In Japanese mythology, there are stories of people bathing in hot springs or sacred waterfalls to purify their bodies and spirits. These waters are connected to nature spirits called kami, and being near them can bring peace, health, and even a new beginning. In Greek myths, the fountain of youth or magical springs could restore a person’s youth and beauty. Heroes sometimes went on long journeys to find such water. One famous example is the River Lethe, where drinking the water caused people to forget their past, offering a kind of spiritual reset or rebirth.
=== In art ===
Water has been a powerful symbol in art for thousands of years. Artists use water to show many different feelings and ideas, such as peace, change, danger, or mystery. In paintings, water often appears as oceans, rivers, rain, or even tears. It can be calm and still, like a quiet lake, or wild and strong, like crashing waves. These images help people feel something when they look at the artwork. For example, a peaceful painting of a pond might make someone feel relaxed, while a stormy sea might show fear or struggle.
In many cultures, water is also used in art to show life and rebirth. In religious art, water is sometimes shown as holy, like in Christian paintings of baptisms, where water is used to wash away sins and begin a new life. In Hindu and Buddhist art, rivers like the Ganges are drawn or carved into temples to show purity and connection to the divine. In ancient times, water also appeared in art to show myths and legends. In Greek and Roman art, gods like Poseidon or Neptune were often shown holding tridents and riding waves or sea creatures. In Egyptian art, the Nile River was a symbol of life and was often painted in scenes of farming, fishing, and ceremonies.
One famous example of water in art is “The Great Wave off Kanagawa” by the Japanese artist Hokusai. This woodblock print shows a huge, powerful wave towering over small boats, with Mount Fuji in the background. The wave looks alive, with curling foam like claws, ready to crash down. Even though the image is full of movement and danger, it is also beautifully balanced and carefully designed. Hokusai may have used the sea not just to show nature’s power, but also the strength and struggle of people facing it. This artwork has become one of the most well-known in the world. Another famous painting that shows water is “Water Lilies” by the French artist Claude Monet. Monet painted many versions of this scene, showing a quiet pond with lily pads, flowers, and reflections of trees and sky on the surface of the water. The soft colors and blurred brushstrokes make the paintings feel peaceful and dreamlike. His paintings help people feel calm and connected to nature, like they are standing next to the pond themselves.
Artists also use water in more practical ways. Watercolor painting, for example, uses water to blend colors in soft, flowing shapes. This kind of painting is known for its light, dreamy look. It is perfect for painting things like clouds, rain, or gentle waves. Some modern artists even create art with water itself, such as fountains, pools, or water installations that change with movement and time. These works let people see, hear, and even touch the water, making the experience feel alive and special.
=== In literature ===
Water shows up in many stories, poems, and myths from all over the world. In books and other writing, water often stands for feelings, life, change, or the unknown. One well-known example is in the book The Old Man and the Sea by Ernest Hemingway. In this story, an old fisherman goes out into the ocean by himself and tries to catch a huge fish. The sea is more than just the place where the story happens. As the fisherman fights to catch the fish, the story talks about human strength, being alone, and having respect for nature. The water shows both danger and deep wisdom.
In Moby-Dick by Herman Melville, the ocean is a big part of the story. The book is about Captain Ahab and his crew as they sail across the sea to find a giant white whale named Moby Dick. The ocean is not just where the story takes place, it also stands for big ideas like the unknown, the power of nature, and life’s deepest questions. Captain Ahab becomes obsessed with hunting the whale, and this makes the sea feel dangerous and full of madness. In The Odyssey by Homer, water is a big part of the story. Odysseus, the main hero, spends many years sailing across the sea to get home after the Trojan War. Along the way, he faces storms, sea monsters, and powerful gods. Each time he travels by water, he faces new problems that test how brave and smart he is. The sea is more than just something to cross, it is a place of adventure, danger, and change. It helps Odysseus grow into a wiser and stronger person. This ancient story shows that water, especially the ocean, was seen as a powerful and magical force, full of meaning and mystery.
In The Secret Garden by Frances Hodgson Burnett, water is shown in a soft and peaceful way. There are moments when rain falls and helps bring the garden back to life. The rain makes the flowers grow and the air feel fresh and clean. For the characters in the story, hearing the rain and feeling the wet earth become signs that things are getting better. The water helps turn the garden from a quiet, lonely place into one that is full of beauty and happiness. In Huckleberry Finn by Mark Twain, the Mississippi River is very important to the story. Huck and Jim, who is an escaped slave, travel down the river on a raft. The river stands for freedom and escape. As they float along, they have many adventures, meet different people, and talk about big ideas like right and wrong, and what it means to be a friend. The river is always moving and changing, just like their journey. It gives them time and space to think and grow. Twain uses the river not just as a way to get from place to place, but as a symbol of the characters’ path to better understand themselves and the world around them.
In poetry, water is often used to show feelings and ideas. In the poem The Rime of the Ancient Mariner by Samuel Taylor Coleridge, a sailor tells a strange and sad story about being lost at sea. The huge ocean around him becomes a symbol of guilt, punishment, and mystery. One famous line from the poem is, “Water, water, every where, And all the boards did shrink; Water, water, every where, nor any drop to drink.” This shows how the ocean, which usually gives life, can also be dangerous and cruel. The poem uses water to teach a lesson, that people must respect nature and the spiritual world. In many myths and legends, water is part of a journey to another world. In the Greek story of Orpheus and Eurydice, Orpheus has to cross a river to enter the underworld and try to bring back his lost love. The river is a border between life and death, showing that water can mark the edge of what people understand. In an African story about Mami Wata, a water spirit appears in dreams and visions. She might bring healing, beauty, or riches, but she must be treated with respect.
=== In movies ===
Water is often used in movies to create powerful emotions, build tension, or act as an challenge for the characters. Directors use water in different ways. It can show danger, mystery, or fear, but it can also show peace, life, or change. In adventure and action movies, water can be exciting or dangerous. It can appear in scenes with storms, floods, or rescues from rivers or oceans. One well-known example is Titanic (1997), where the ocean is not only the setting but also a major cause of the disaster. At first, the sea looks calm and beautiful, but later, the cold water becomes a threat as the ship sinks. In fantasy and science fiction movies, water can be strange or magical. For example, in Avatar: The Way of Water, the ocean is a place full of unusual creatures and emotional moments. It is shown as both a home and a challenge for the characters.
In the animated movie Moana, water is shown as something that can move on its own and help the main character. The ocean guides Moana as she tries to save her island. It helps her when she is scared and keeps her safe from harm. In the movie, water acts like a helper. It also links Moana to her ancestors, who also sailed the oceans. The ocean in this story is not something to be afraid of but something to understand and rely on. In Finding Nemo (2003), the entire story takes place underwater. The ocean is full of sea life, reefs, and dangers. It shows that water can be both fun and dangerous. The underwater setting is important to the whole story. In Cast Away (2000), the ocean separates the main character from other people after a plane crash. The ocean becomes a challenge he must face, and it is also the way he must return to his normal life.
Water is also used in movies to show feelings or deeper meanings. In many dramas, rain can show sadness, being alone, or a big change in the story. For example, in The Notebook, the rain scene is full of strong emotion and shows an important moment between two characters. Water can also stand for a new beginning or change. In horror movies, water can make scenes more tense or scary. Dark lakes, bathtubs, or storms can trap people or hide something dangerous. In Jaws, for example, the ocean looks calm, but a shark is hiding below. People swim without knowing the danger, which creates fear and suspense. Water also works well in movies because it moves, reflects light, and makes sounds. Whether it is big waves, gentle rain, or quiet ponds, water adds something special to a scene. It helps tell the story in a visual way, sometimes more clearly than words can. This makes water one of the most useful natural elements in filmmaking.
=== Dihydrogen monoxide parody ===
The dihydrogen monoxide parody began as a funny joke in the early 1990s. It was meant to show how using big science words can confuse people and make safe things sound dangerous. "Dihydrogen monoxide" is just a fancy way of saying water. The word “dihydrogen” means two hydrogen atoms, and “monoxide” means one oxygen atom. That adds up to H₂O, which is the chemical formula for water. Even though it is just water, calling it “dihydrogen monoxide” makes it sound like a harmful chemical. This joke was used to show that many people do not always understand science words, and they can be tricked if something is explained in a dramatic or serious-sounding way.
One of the earliest and most famous uses of this joke happened in 1997, when a high school student named Nathan Zohner gave a science presentation titled "How Gullible Are We?". In his report, he described all the dangers of “dihydrogen monoxide”. Like causing burns (as steam), contributing to erosion, being found in cancer cells, and even causing death when inhaled. He did not say that it was just water until the very end. Out of 50 students who listened to his presentation, 43 voted to ban the chemical. Nathan’s project became famous, and it showed how people can be easily tricked if they do not have enough scientific knowledge or critical thinking.
Before that, versions of the joke had appeared in internet forums and emails, especially as the internet was growing in the 1990s. People used the parody to make fun of how the media, politicians, or even environmental activists might sometimes overreact to scientific information without fully understanding it. Over time, the joke spread widely and became part of internet culture. It is often used today in classrooms, debates, or websites to teach people to read carefully and to question information that sounds too dramatic or scary. The DHMO parody continues to be shared today, often as a reminder that how we present information really matters. If something is said with the right tone, long words, or half-truths, people might believe anything, even that water is dangerous. It is a funny but important lesson in science literacy, skepticism, and not jumping to conclusions without understanding the full picture. The website DHMO.org is a joke website which lists the harmful effects of water (DHMO), answers questions, and calls for it to be banned, among other things.
=== In music ===
Water has always been a big inspiration in music because it connects to so many feelings and ideas. People all over the world use water as a symbol in songs to show emotions like peace, sadness, change, power, or even mystery. Just like water can be calm or stormy, music about water can be soft and gentle or loud and intense. For example, a calm river or gentle rain might be used to create a peaceful feeling, while crashing waves or a flood might show strong emotions like anger, heartbreak, or chaos. Water can represent the flow of life, the passage of time, or the feeling of being overwhelmed by something big.
In classical music, composers have often used water to paint pictures with sound. For example, famous composers like Claude Debussy wrote pieces such as La Mer (The Sea), where the music was inspired by the sea. Another example is Frédéric Chopin’s "Raindrop Prelude", where repeating notes sound like gentle raindrops falling. These pieces do not use words, but the music still makes listeners feel like they are near water. In modern times, pop, rock, and folk songs also use water in their lyrics. Songs like Bridge Over Troubled Water by Simon & Garfunkel or River by Joni Mitchell use rivers and storms as ways to talk about emotions and life problems. In these songs, water can be both the problem and the solution. It can pull someone down, or it can wash their pain away.
In many cultures, water is tied to spiritual or emotional cleansing, so music about water is often healing or thoughtful. In African, Asian, and Indigenous traditions, water songs are sometimes sung during rituals, rain dances, or prayers, asking nature for help or giving thanks for life. In blues music, rivers often appear as symbols of sorrow or escape, especially in songs from the American South, where the Mississippi River became a symbol of travel, freedom, and sometimes grief. In reggae and Caribbean music, the sea and rain show up in joyful, laid-back songs that celebrate nature and the rhythm of island life.
Water even affects how music sounds. In some electronic or ambient music, water sounds like waves, rain, or dripping are added to create a relaxing background. These sounds are used in meditation music or sleep playlists because they help people feel calm and safe. Music therapists also use water sounds to help people reduce stress or connect with their emotions.
== Related pages ==
== Notes ==
== References ==
== Other websites ==
Importance of Water Archived 2021-09-28 at the Wayback Machine
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At least 81 people have been confirmed dead in central Texas and another 41 are missing following flash floods on Friday. Sixty-eight of the fatalities, including 28 children, were in Kerr County, where a riverside Christian girls' camp was deluged. Ten girls and a counsellor from Camp Mystic are still missing. There are five confirmed casualties in Travis County, three in Burnet County, two in Williamson County, two in Kendall County and one in Tom Green County. Figures are changing quickly as rescuers continue to search for the missing, and officials say the death toll is certain to rise. Of those recovered in Kerr County, 18 adults and 10 children have yet to be formally identified. More storms are expected in the next 24-48 hours in the region, which could hamper rescue teams who are already facing venomous snakes as they sift through mud and debris. Three days after the inundation, one of the largest search-and-rescue efforts in recent Texas history was shifting towards a recovery operation. Texas Governor Greg Abbott said on Sunday that authorities would "stop at nothing" to ensure every missing person is found. "It was nothing short of horrific to see what those young children went through," said Abbott, a day after he toured the area. A major focus of the search has been Camp Mystic, a popular summer camp for girls perched on the banks of the Guadalupe River, which suffered significant damage. The catastrophe unfolded before daybreak on Friday as the river rose 26ft (8m) in the span of just 45 minutes while most campers were asleep. Several young campers and the camp's longtime director, Richard "Dick" Eastland, are among the dead. Greg Froelick, a former Navy Seal and volunteer with the rescue group 300 Justice, is helping the effort to find survivors. Speaking to the BBC, he said he had heard of victims being found up to eight miles downriver from where Camp Mystic once stood. He said he has seen "clothing and items from the camp dressers scattered everywhere, up and down the river". There is also uncertainty about how many other people were camping in the area for the Fourth of July weekend - and how many may have been swept away in the floods. A two-lane highway that skirts the Guadalupe River and connects the city of Kerrville to Camp Mystic is a scene of devastation. Ravaged homes are surrounded by fallen trees and furniture scattered across lawns. Fences are toppled and utility lines down in some areas. President Donald Trump signed a major disaster declaration on Sunday for Kerr County, activating the Federal Emergency Management Agency to Texas. He also said he would probably visit the state on Friday. "We're working very closely with representatives from Texas, and it's a horrible thing that took place, absolutely horrible," Trump said on Sunday in New Jersey. On the ground, local residents are stepping up to support relief efforts - collecting supplies, offering shelter, and doing what they can to help neighbours displaced by the storm. Alma Garcia drove in from the city of San Antonio to deliver home-cooked meals to residents and volunteers helping with the clean-up effort. The BBC saw her pull over on the side of the road and take off a top layer T-shirt to give to a resident. "She was all wet, I told her she's going to need it," Ms Garcia told the BBC. Local resident Perla started collecting clothes and shoes on Friday after she finished her shift at Walmart. She dropped them off at a shelter the next morning. "I've never seen something like this before," she told the BBC. Meanwhile, well wishes poured in from around the world. In Rome, Pope Leo XIV offered special prayers on Sunday for the bereaved in Texas. "I would like to express sincere condolences to all the families who have lost loved ones, in particular their daughters who were in summer camp, in the disaster caused by the flooding of the Guadalupe River in Texas in the United States," the pontiff said. "We pray for them." Angélica Casas and Alex Lederman contributed to this report
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