Many people confuse yam and sweet potato. Yam is a starchy root and sweet potatoes are fleshy and varies in color from white to orange to purple even. It is not a potato either and as such should not be used as substitutes in cooking. Sweet potatoes are rich in beta carotene, a type of antioxidant that gives the skin of the potatoes its orange color.
Beta carotene is a source of vitamin A. It helps to make skin healthy and may also help against skin damage from ultraviolet (UV) rays. Do not store sweet potatoes in the refrigerator rather than store it in a cool, dry place like the basement.