Ultraviolet (UV) radiation is the major environmental risk factor for nonmelanoma skin cancer and is a suspected risk factor for melanoma. Avoiding overexposure to direct sunlight during the peak daylight hours, wearing protective clothing, and applying sunscreen are ways to protect the skin. To provide clinicians with the tools to advise patients and to answer their inquiries, including which sunscreen to use, we review UV radiation's effect on the skin, how sunscreens block UV light, current recommendations on sunscreen use, and new sunscreen labeling requirements.