Melanoma usually refers to malignant melanoma, which usually arises from benign dark pigmented nevi or from gradual progression, friction, and deterioration of skin pigmentation spots, all of which are malignant diseases. Melanoma is a representative of malignancy and needs to be taken seriously by patients, who should pay attention to the condition, symptoms, and prevent for pigmented nevi or pigmented spots of larger scope, observe them regularly, and visit them regularly. If it is a benign lesion called nevus nigricans, the two mean different things. A nevus of black pigmentation can be manifested as a skin nevus in some parts, or as a mucosal pigmentation spot of mucosal tissue, or as a nail nevus on the nail, called nail mother nevus, which is pigmentation and not melanoma.