Five major types of precipitation are rain, freezing rain, snow, sleet, and hail.
Rain is the most common form of precipitation. It occurs when a portion of the atmosphere becomes saturated with moisture such that water condenses in the form of droplets that are heavy enough to fall to the Earth's surface.
Freezing rain is rain that forms and falls under normal conditions but there is a blanket of freezing air at the surface that causes the liquid rain to freeze upon contact with raised surfaces like power lines and tree limbs.
Snow is formed when relatively warmer moist air rises upward rapidly and comes into contact with freezing air. The moisture quickly freezes into ice particles called snow.
Sleet is composed of tiny ice pellets that are larger and heavier than snowflakes. This occurs when snowflakes fall through a layer of above freezing air and melt into rain. But the rain then refreezes as it falls to the surface in the form of sleet.
Hail is like a larger form of sleet. Strong updrafts from storm systems can blow the ice pellets back upwards where they acquire more ice. The more time that the pellets are aloft in the atmosphere the larger in size they will become. Finally, the balls of ice are too large and heavy to remain aloft and fall to the surface as hailstones.