Skin cancer is the most common cancer in the United States, and most cases are preventable. Persons with certain genetic risk factors, including having a lighter natural skin color; blue or green eyes; red or blonde hair; dysplastic nevi or a large number of common moles; and skin that burns, freckles, or reddens easily or becomes painful after time in the sun, have increased risk for skin cancer. Persons with a family or personal history of skin cancer, especially melanoma, are also at increased risk. Although these genetic factors contribute to individual risk, most skin cancers are also strongly associated with ultraviolet (UV) radiation exposure. Most UV exposure comes from the sun, although some persons use UV-emitting indoor tanning devices (e.g., beds, booths, and lamps).