The water cycle is the path water follows as it moves around Earth again and again. This cycle does not have a true beginning or end, but many people start by looking at the sun's role.

When the sun warms oceans, lakes, rivers, and puddles, some water changes into a gas called water vapor. This process is called evaporation. Plants also release water vapor into the air. Together, these changes add moisture to the atmosphere.

High in the sky, air is cooler. There, water vapor changes back into tiny drops of liquid water or ice. This is called condensation. Many tiny drops together can form clouds.

When the drops or ice crystals in clouds grow heavy enough, they fall to Earth as precipitation. Precipitation can be rain, snow, sleet, or hail. Some of this water soaks into the ground. Some flows into streams, rivers, and oceans.

Then the cycle continues. Water can evaporate again and return to the air. Because the water cycle keeps moving water from place to place, it helps supply fresh water to living things all over Earth.