When water vapour in the air condenses, they form clouds. When these clouds become heavy with the water droplets, it falls on the Earth's surface as precipitation.
There are three types of precipitation: rainfall, snowfall and hailstones.
Rainfall is the precipitation of water droplets in the form of rain.
Snowfall occurs when the temperature of a place is below 0℃ and falls as snow.
Hailstones form during thunderstorms when the temperature inside huge clouds is below the freezing temperature.