What is water?

Water molecule details.

Water is a colorless and odorless substance found all over Earth. Water is made up of billions of molecules. Each molecule is made of one oxygen and two hydrogen atoms held together by strong covalent bonds.  

Water is found in three different forms on Earth – gas, solid, and liquid.  The form water takes depends on the temperature. Water on our planet flows as liquid in rivers, streams, and oceans; is solid as ice at the North and South Poles; and is gas (vapor) in the atmosphere. Water is also underground and inside plants and animals. All living things need water in some form to survive on Earth.  People can go weeks without food, but can live only a few days without water. 

Water is an important resource with many uses including food production, cleaning, transportation, power generation, recreation, and more.

Contributor – Jennifer R. Fetter, Penn State Extension