Vitamin D is also known as an anti rickets vitamin, the most important of which are vitamin D2 and vitamin D3. Vitamin is a steroid derivative, belongs to fat-soluble Vitamin. Vitamin D is a derivative of vitamin D by ultraviolet irradiation, and it is found in animals and plants. Human skin contains a substance called 7-dehydrocholesterol, which is converted to vitamin D by The sun's ultraviolet rays.