Skin cancer is one of the most common cancers in the world. It is is an abnormal growth of skin cells. They most often develop on skin exposed to the sun but can also occur on areas of your skin not ordinarily exposed to sunlight. Skin cancers can appear as moles, scaly patches, open sores, or raised bumps. These signs can vary, depending on the form of skin cancer present. There are three major types of skin cancer — basal cell carcinoma (most common), squamous cell carcinoma and melanoma. Checking your skin for suspicious changes can help detect skin cancer at its earliest stages. Early detection of skin cancer gives you the greatest chance for successful skin cancer treatment.