Water is a thing.
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth 's streams , lakes , and oceans , and the fluids of most living organisms . Water strictly refers to the liquid state of that substance , that prevails at standard ambient temperature and pressure ; but it often refers also to its solid state ( ice ) or its gaseous state ( steam or water vapor ) . It also occurs in nature as snow , glaciers , ice packs and icebergs , clouds , fog , dew , aquifers , and atmospheric humidity . Large quantities of water , ice , and steam are used for cooling and heating , in industry and homes . Water is also central to many sports and other forms of entertainment , such as swimming , pleasure boating , boat racing , surfing , sport fishing , and diving .