The water cycle describes how water is continually recycled on Earth. Water evaporates from oceans and other surfaces, rises into the atmosphere as vapor, cools and condenses to form clouds, and falls back to Earth's surface as precipitation. This cycle has occurred for billions of years, so the water we drink today is the same water that was present when dinosaurs lived millions of years ago, as water is constantly recycled through the atmosphere and lithosphere rather than being used up or replenished.