Melanoma is a serious form of skin cancer. But it is not nearly as common as some other types of skin cancer. It occurs when the pigment-making cells (melanocytes) change and become cancer. Melanocytes are skin cells responsible for giving color to the skin. Clusters of melanocytes form moles, which are very common. Melanoma can develop in people of all ages. But it is most often seen in older adults and in young adults.

Most moles are harmless. Some melanomas start from moles, but others do not. If you have many moles or atypical moles (dysplastic nevi), you have a higher risk of developing melanoma.

Have any mole checked by a healthcare provider right away if it: is not round; has irregular edges or different colors; looks different from your other moles; is new or growing; or is itching, painful, or bleeding.

Melanoma often spreads quickly. It may cause death if not treated. But if found early, it can often be cured. Finding and treating it early is critical.

Use a broad-spectrum sunscreen with an SPF of at least 30. Put it on exposed skin every day you plan on being outside. This is true even if you aren’t going to be in the sun. You need to wear sunscreen year-round, even when it's cloudy.

SPF only measures protection against UVB rays, which cause sunburn. UVA rays are also harmful. They can go deeper into the skin. Use a broad-spectrum sunscreen that protects against both UVA and UVB rays.

Put sunscreen on any area exposed to the sun at least 15 minutes before going outside.

The skin is the most common site. But melanoma can also start in the eye, inside the mouth, in the genital or anal area, or even in organs inside the body.