Precipitation is important because it helps maintain theatmospheric balance. Without precipitation, all of the land on the planet would be desert. Precipitation helps farmers grow crops and provides a fresh water supply for us to drink.
Precipitation can also be damaging. Too much rain and snow can cause severe flooding and lots of traffic accidents. Hail can damage crops and cars. Freezing rain and sleet can destroy trees and power lines.
The opposite of precipitation is evaporation.
source: windows to the universe