Percolation is a process in the water cycle where water moves through the soil and its layers by gravity and capillary forces. It occurs after infiltration, which is the process of water entering the soil surface. As the water percolates into the deeper layers of the soil, it reaches groundwater. Percolation is an important process in the water cycle because it helps to recharge aquifers, which are underground layers of rock or sediment that hold water. Aquifers are important sources of water for human consumption and irrigation. Percolation also helps plants grow by providing them with water stored underground.