Vitamin D3, also known as Cholecalciferol, is a fat-soluble vitamin that plays a critical role in calcium absorption, bone health, and immune system function. It helps regulate calcium and phosphorus levels in the body, supporting strong bones, teeth, and overall skeletal health. Vitamin D3 also enhances immune responses, reducing the risk of infections and supporting cardiovascular health. It is often referred to as the "sunshine vitamin" because the body can produce it when exposed to sunlight. However, supplementation is often necessary, especially in regions with limited sunlight or for individuals with specific health needs.