C is for color. Your doctor should check changes in the color of your skin. D is for diameter. The diameter is the length of a mole from any end to the opposite end. If this increases, or if it is bigger than a pencil eraser, you should have it checked.
Melanomas are much more common on skin that is exposed to sunlight.
All persons, but particularly those with fair skin, should avoid sunburn. Surgery is used to treat melanoma. The primary growth must be removed. If nearby lymph nodes are involved, it may be necessary to remove those also. For local malignant melanoma, survival rates are very good.