Calcium is the mineral critical for building strong bones and teeth. It plays a vital role in maintaining bone density and structure. Approximately 99% of the body's calcium is stored in bones and teeth, where it helps to provide strength and support. Adequate calcium intake is essential throughout life, particularly during childhood, adolescence, and older adulthood when bone density can decline. Dairy products, leafy greens, and fortified foods are common sources of calcium, and it is important to balance calcium intake with vitamin D, as this vitamin enhances calcium absorption in the body.