A mole (or melanocytic naevus) is an abnormal collection of pigment cells present within the skin, which is extremely common in every individual. Most people are born with a few moles and may develop more during their lives. A few of these moles, called congenital melanocytic naevi, are usually present at birth. But most develop spontaneously or are caused by exposure to sunlight and tend to appear on those areas of the skin that catch the most sunlight. It is important to monitor nevi for indicators of transformation.

Moles that are suspicious looking should be removed by excision biopsy. Smaller moles can be lasered off for cosmetic reasons.