The water cycle is a term that describes how water moves cyclically between the seas, the atmosphere and the surface of planet Eearth. Seas and oceans are central to this cycle, as most of the planet's atmospheric water both evaporates from and rains into them.

Atmospheric water vapor is also distributed to air masses that are located above the ground. From these air masses, the water will rain down to the surface of the Earth in the form of either rain or snow. After raining down, the majority of this water will return to the planet's oceans through rivers. 

Some water is absorbed by the soil. Some of this water evaporates back into the atmosphere either directly or through plants, wheareas some of the water sinks down to the ground, forming reserves of groundwater.