Editing Water

{{SHORTDESC:Essential chemical compound for life}}

'''Water''' is a chemical substance with the formula '''H₂O'''. It is vital for all known forms of life and covers about 71% of the Earth's surface, primarily in [[ocean]]s, [[lake]]s, [[river]]s, and other bodies of water. Water exists in various forms, including [[liquid]], [[solid]] ([[ice]]), and [[gas]] ([[water vapor]]).<ref>{{cite news |title=The importance of water for life |work=Science Daily |date=2023-05-10 |url=https://www.sciencedaily.com/releases/2023/05/230510102938.htm}}</ref>

== Physical and Chemical Properties ==
Water is a polar molecule with a bent structure, which gives it unique properties such as a high [[specific heat capacity]], excellent [[solvent]] capabilities, and surface tension. These properties make it critical for [[climate regulation]], [[plant growth]], and various biological processes.

Water's states of matter:
* '''Liquid''': Found in oceans, rivers, and rainfall.
* '''Solid''': Ice is formed when temperatures drop below 0°C.
* '''Gas''': Water vapor exists in the atmosphere and is a key part of the [[water cycle]].

== Distribution on Earth ==
The Earth's water distribution includes:
* '''Oceans''': 97.5% of Earth's water is saline.
* '''Freshwater''': Only 2.5% is freshwater, found in [[glacier]]s, [[aquifer]]s, and [[river]]s.<ref>{{cite article |title=Global water distribution statistics |work=Nature |date=2022-11-15 |url=https://www.nature.com/articles/global-water-distribution}}</ref>

=== Water Cycle ===
The [[water cycle]] describes the continuous movement of water within the Earth and atmosphere. The main stages include:
1. '''Evaporation''': Water changes from liquid to gas.
2. '''Condensation''': Water vapor cools to form clouds.
3. '''Precipitation''': Rain or snow falls back to the Earth's surface.
4. '''Runoff and infiltration''': Water returns to rivers, oceans, or underground reservoirs.

== Biological Importance ==
Water is essential for [[life]] and plays a critical role in:
* '''Human health''': The human body is about 60% water, essential for hydration, digestion, and temperature regulation.
* '''Plant growth''': Plants use water in [[photosynthesis]] to produce energy.
* '''Ecosystems''': Aquatic ecosystems depend entirely on water for survival.<ref>{{cite news |title=Water and its role in ecosystems |work=The Guardian |date=2024-02-18 |url=https://www.theguardian.com/environment/water-ecosystems}}</ref>

== Human Use ==
Water is indispensable for:
* '''Agriculture''': Used for irrigation in crop production.
* '''Industrial processes''': Necessary in manufacturing, cooling, and energy generation.
* '''Drinking water''': Clean, safe water is vital for human health, with over 2 billion people lacking access to safe drinking water.<ref>{{cite article |title=Global water crisis and its effects |work=World Health Organization |date=2023-08-09 |url=https://www.who.int/news/water-crisis}}</ref>

== Challenges ==
Despite its abundance, water faces several challenges:
* '''Pollution''': Industrial waste and [[plastic pollution]] harm water sources.
* '''Scarcity''': Over 1.2 billion people experience [[water scarcity]] due to climate change and overuse.
* '''Climate change''': Alters precipitation patterns, leading to droughts and floods.<ref>{{cite news |title=How climate change impacts water resources |work=BBC News |date=2023-12-01 |url=https://www.bbc.com/news/water-climate-impact}}</ref>

== See Also ==
* [[Hydrology]]
* [[Drinking water]]
* [[Water scarcity]]
* [[Environmental conservation]]
* [[Oceanography]]

== References ==
{{Reflist}}

== External Links ==
* [https://www.unicef.org/water UNICEF on Water and Sanitation]
* [https://www.who.int/water World Health Organization – Water and Health]