Calcium (Ca²⁺) is a chemical element and an essential mineral found in many foods. It plays a crucial role in various bodily functions, including building and maintaining strong bones and teeth. Calcium is also important for muscle contraction, nerve signaling, and blood clotting. In nature, calcium is commonly found in rocks and minerals, such as calcite and gypsum. It is the fifth most abundant element in the universe and is vital for living organisms. Dietary sources of calcium include dairy products, leafy greens, and fortified foods, making it important for overall health and development.