Percolation is the process of water seeping downward from the surface of the earth into the soil and rocks and becoming groundwater. Plants use some of this groundwater but most of it collects in pore spaces around soil and sediments and in rocks in areas called aquifers. This water is pumped to the surface by humans for use. In some places, the groundwater reaches the surface by itself as a natural spring. It can remain in the ground for hundreds of years before it is used.
Water droplets collide with each other in the clouds to form larger drops.
Precipitation can be found in either a solid or liquid state depending upon the temperature. Rain, snow, sleet, snow, and hail are common forms of precipitation. In the desert it is common to see rain that is falling evaporate before it reaches the ground. This precipitation is called virga. It includes water in oceans, lakes, rivers, ponds, marshes, swamps, glaciers, snow fields, etc.