Melanoma is a cancer of the pigment producing cells in the skin known as melanocytes. Cancer is a condition in which one type of cell grows without limit in a disorganized fashion, disrupting and replacing normal tissues and their functions, much like weeds overgrowing a garden. Normal melanocytes reside in the outer layer of the skin and produce a brown pigment called melanin, which is responsible for skin color. Melanoma occurs when melanocytes become cancerous, grow, and invade other tissues.
Melanoma begins on the surface of the skin where it is easy to see and treat. If given time to grow, melanoma can grow down into the skin, ultimately reaching the blood and lymphatic vessels, and spread around the body (metastasize), causing a life-threatening illness. It is curable when detected early, but can be fatal if allowed to progress and spread. The goal is to detect melanoma early when it is still on the surface of the skin.