Skin that is exposed to the sun can become damaged, causing skin cells to uncontrollably divide. When this occurs in the skin’s outermost layers, it is known as squamous cell carcinoma. Basal cell carcinoma occurs when the affected cells are just below the squamous cells in the skin. The cells that make the brown pigment melanin, which gives skin its brown color, are called melanocytes, and when they become cancerous, the cancer is called melanoma. Squamous and basal cell cancers spread around the place where they start but usually do not spread to other parts of the body. Melanoma accounts for only 2% of skin cancers but spreads rapidly throughout the body and can cause death. It is best to find and remove these cancers early. It is not known if screening (deliberately looking for these cancers on a regular basis) helps detect melanoma early enough to help people.