This document discusses the hydrosphere, which is the water sphere that surrounds the Earth. The hydrosphere comes from the Latin word "hydro" meaning water, and it covers about 71% of the Earth's surface. Water is essential for life as it makes up 75% of living cells and allows chemical reactions to occur. The hydrosphere also regulates climate, provides habitat, and is important for human and industrial use. However, water pollution and misuse threaten the hydrosphere. We must avoid pollution and misusing water to protect this critical part of our planet.