Rain is actually part of a bigger part of the weather called precipitation, which means any form of water that falls to the earth like rain, snow, drizzle, hail and sleet. Water can be in the atmosphere, on land, in the ocean and even underground. It gets used over and over and over again through what is called the water cycle. In this cycle water changes from liquid, solid and gas (which is water vapor). The water vapor then gets into the atmosphere through a process called evaporation. This then turns the water that is at the top of oceans, rivers and lakes into water vapor in the atmosphere using energy from the sun. This vapor can also from snow and ice too. The water vapor rises in the atmosphere and there it cools down and forms tiny water droplets through something called condensation. These then turn into clouds. When they all combine together, they grow bigger and are too heavy to stay up there in the air. This is when they will fall to the ground as rain, or maybe snow or hail by gravity.