The vitamin synthesized by the skin when exposed to sunlight is Vitamin D. This essential nutrient is produced when ultraviolet (UV) rays from sunlight interact with a cholesterol derivative in the skin, resulting in the formation of Vitamin D3, also known as cholecalciferol. Vitamin D plays a crucial role in maintaining healthy bones by helping to regulate calcium and phosphorus levels in the body. It also supports immune function and has other health benefits. Due to its reliance on sunlight, many people may need to consider dietary sources or supplements, especially in regions with limited sun exposure.