Skin cancer is the abnormal growth of skin cells that usually develops on areas of the skin that are frequently exposed to the sun. It affects people of all skin tones, including people with dark complexions. Signs of skin cancer include moles and/or lesions on different parts of the body, and the way they look and where they appear depends on the type of skin cancer. The three major types of skin cancer are basal cell carcinoma, squamous cell carcinoma and melanoma, with melanoma being the most dangerous type of skin cancer. Early detection provides the greatest chance for successful treatment.