The vitamin produced by the skin in sunlight is vitamin D. When exposed to ultraviolet (UV) rays from the sun, the skin synthesizes vitamin D from cholesterol. This essential nutrient plays a critical role in calcium absorption, bone health, and immune system function. Adequate levels of vitamin D are vital for overall health, helping to prevent conditions like rickets in children and osteoporosis in adults. However, excessive sun exposure can lead to skin damage and increase the risk of skin cancer, highlighting the importance of balanced sun exposure.