The water cycle describes the continuous movement of water on, above, and below the surface of the Earth. The sun's energy drives the water cycle by evaporating water which rises into the atmosphere. Water vapor then condenses to form clouds and precipitation falls back to Earth through processes like rain or snow. The water is then collected in bodies of water like oceans, lakes, and rivers, where it can evaporate again and restart the cycle, ensuring a constant supply of fresh water for living things.