The vitamin synthesized by the skin in response to sunlight is Vitamin D. When ultraviolet (UV) rays from the sun hit the skin, they convert a cholesterol compound called 7-dehydrocholesterol into Vitamin D3 (cholecalciferol). This process is crucial for various bodily functions, particularly for maintaining calcium levels and supporting bone health. Vitamin D plays a vital role in immune function and has been linked to the prevention of various diseases. However, adequate sun exposure and dietary sources, like fatty fish and fortified foods, are essential for optimal Vitamin D levels, especially in regions with limited sunlight.