Calcium is a chemical element with the atomic number 20 and symbol Ca. It is a silvery-white metal that is highly reactive and forms compounds with a wide variety of other elements. In nature, calcium is found in many minerals, including limestone, gypsum, and fluorite.

In the human body, calcium is an essential mineral that is primarily stored in bones and teeth. It plays a crucial role in maintaining the structural integrity of bone tissue and in overall bone health. Calcium also plays a key role in muscle contractions, nerve function, and the release of hormones. The recommended daily amount of calcium for adults is between 1000-1300mg, which can be obtained through dietary sources such as dairy products, leafy greens, and fortified foods.