Water is a necessary resource for life that exists in three states: liquid, solid, and gas. It can be found in oceans, rivers, lakes, underground, as snow in mountains, and as ice at the poles. The water cycle describes how water evaporates from bodies of water into vapor due to heat from the sun, condenses into clouds, and falls back to earth as precipitation where it collects in bodies of water to repeat the cycle. Proper water management through reservoirs is important, as not all water is safe for drinking and some areas face water scarcity.