Skin cancer is a disease in which cancer (malignant) cells are found in the outer layers of your skin. Your skin protects your body against heat, light, infection, and injury.

The skin has two main layers and several kinds of cells. The top layer of skin is called the epidermis. It contains three kinds of cells: flat, scaly cells on the surface called squamous cells; round cells called basal cells; and cells called melanocytes, which give your skin its color.

Sunburn and ultraviolet (UV) light can damage your skin, and this damage can lead to skin cancer. There are, of course, other determining factors, including your heredity and the environment you live in. However, both the total amount of Sun received over the years, and overexposure resulting in sunburn can cause skin cancer.

Tanning is your skin's natural response to UV light. It is a reaction, just like an allergic reaction, to prevent further injury to your skin from the Sun though it does not prevent skin cancer. Skin cancer is very slow to develop.

If there is a history of skin cancer in your family, you have fair skin, or you have a northern European heritage you are probably at a higher risk. Also the elevation, latitude, and cloud cover of the area you live in effect susceptibility to skin cancer. UV light gets stronger as the elevation increases. The thinner atmosphere at higher altitudes doesn't filter UV as much as it does at lower altitudes. The sun's rays are also stronger near the equator.