H20 is the chemical formula for WATER, which is composed of two hydrogen atoms and one oxygen atom. It is the most abundant compound on Earth and is essential for all known forms of life. WATER is a liquid at standard temperature and pressure, but it can also exist as a solid or gas. It is an important part of many processes in nature, including the hydrologic cycle, weathering, and erosion. WATER is also used in many industries, such as agriculture, manufacturing, and energy production.