Do you know why Earth is referred to as the “blue planet?” This is because about 75 percent of Earth is covered with water, so the planet looks blue when viewed from outer space. Water is found in the planet’s oceans, seas, lakes, springs, and other bodies of water. These water forms comprise the hydrosphere, or the part of Earth that is made up of all the water that can be found on the planet, including those on its surface, under the ground, or even in air.

Water is one of the most important substances on Earth. All living things need water in order to survive. Without it, there would be no life on Earth.