Melanoma is a dangerous kind of skin cancer. It starts in the cells that make the dark colour in skin. People sometimes say it causes cancer, but it is the cancer: a bad growth, not a harmless mark that later turns into something else. It may look like a new mole, or an old mole that changes shape, colour, or size. Doctors take it seriously because it can spread to other parts of the body if it is not found early. It is a medical word you will hear at the doctor's and in health news. Most moles are not melanoma; the thing to notice is change.