Water

Water is a chemical compound made of two hydrogen atoms and one oxygen atom, giving it the formula H₂O. It covers about 71% of Earth's surface and is essential for all known forms of life. Water exists naturally as a solid, liquid and gas, allowing it to circulate continuously through the water cycle. It evaporates from oceans, lakes and soils, forms clouds through condensation, then returns to the surface as rain, snow or hail.

One of its most remarkable properties is its ability to dissolve a wide variety of substances, making it an excellent solvent. This characteristic allows nutrients, minerals and gases to move through living organisms and the environment. Pure water is colorless, odorless and tasteless, although natural water usually contains dissolved minerals and other substances that influence its composition and taste.

Water plays a central role in nature, human health and many industrial activities. It helps regulate Earth's climate because it can absorb and release large amounts of heat with only small changes in temperature. In living organisms, water transports nutrients, removes waste, supports chemical reactions and helps maintain a stable internal temperature. It is also indispensable for agriculture, food production, energy generation and manufacturing.

Although water is abundant on Earth, only a small fraction is readily available as fresh water for human use, since most is found in oceans or trapped in ice. Protecting rivers, lakes, groundwater and wetlands from pollution and excessive use is therefore essential to ensure clean water for ecosystems and future generations.