Melanoma is a cancer of cells in the skin that produce a brown pigment called melanin. Risk factors for melanoma include a family history of melanoma, large numbers of moles and freckles, sun sensitivity (light skin color, tendency to burn, and inability to tan), and exposure to ultraviolet (UV) radiation from the sun or sunlamps and tanning beds. The number of people who get melanomas is increasing faster than any other type of cancer in the United States. Some people think that this number is increasing mainly because people are spending more time in the sun.