"Ca" is the chemical symbol for calcium, a vital element found in the Periodic Table with the atomic number 20. It is a soft, gray metal that belongs to the alkaline earth metals group. Calcium is essential for various biological functions, including the formation of bones and teeth, muscle contraction, and nerve signaling. In nature, calcium is commonly found in minerals such as calcite and gypsum. It is also abundant in foods like dairy products, leafy greens, and nuts. Adequate calcium intake is crucial for maintaining strong bones and overall health, especially in growing children and aging adults.