This document provides an overview of water, including its chemical composition, states, sources, uses, and the water cycle. It notes that water is made of hydrogen and oxygen atoms, and covers three fourths of the Earth's surface. However, only 0.01% is available for human consumption due to most being trapped in oceans, glaciers, or unavailable due to pollution. The water cycle involves the four stages of evaporation, condensation, precipitation, and collection, through which water circulates from land to sky and back again.