In meteorology, precipitation occurs when any form of water, usually in liquid or solid state, falls from clouds in the sky to the ground. There are various ways this happens.
The most common form of precipitation is rain, which is also the only liquid state. It is an important phase of the Earth’s water cycle, replenishing most of the planet’s bodies of fresh water. Rainfall can be as light as a drizzle or so heavy that it can result in flooding.
Snow occurs almost every time there is rain, but this precipitation form usually just melts into rain due to being exposed to non-freezing temperature in the air. If the temperature is low enough, virga or flakes of ice water descend.
When rain passes through layers of below freezing conditions in the air, the droplets become super-cooled and solidify into freezing rain. Upon reaching the ground or objects on the surface, the liquid freezes and becomes a coat of ice called glaze.
Hailstones can only be formed in winter or sub-freezing weather. It is purely solid precipitation, unlike sleet, and can have a diameter as small as a pea or as big as a grapefruit.