The journey of water on Earth is very important. Water is always moving. This movement is called the water cycle. First, the sun heats the water in oceans, rivers, and lakes. The warm water goes up into the sky as a gas. This process is called evaporation. In the sky, the air is cold. The gas becomes small drops of water. These drops make clouds. This is condensation. When the clouds are heavy, the water falls back to the Earth as rain or snow. This is precipitation. The water goes into rivers and returns to the ocean. This final step is collection. The cycle then begins again. The water cycle is essential for all life on our planet.