Water is a chemical substance with the chemical formula H20. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds.
Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near hydrophilic surfaces. Under nomenclature used to name chemical compounds, dihydrogen monoxide is the scientific name for water, though it is almost never used.