The prcoess in which water evaporated and falls on the land as rain and later flows back into the sea via rivers is know as the water cycle.

Water cycle mainly involves four steps namely transpiration, evaporation, condensation and precipitation. In other words we can say that water evaporates from its sources like rivers, ponds, sea to form white clouds (condensation), when the dust particles and smoke is mixed with these white clouds it forms black clouds which in turn gives us rain (precipitation). During this process the water that falls on the ground in the form of rain does not immediately flow into the sea, some amount of the water seeps into the soil and becomes a part of the ground water reservoir of fresh water.