Melanin is a natural substance that gives color (pigment) to hair, skin, and the iris of the eye. It is produced by cells in the skin called melanocytes.
Melanin also helps protect the skin from the sun.
Habif TP, ed. Principles of diagnosis and anatomy. Clinical Dermatology. 5th ed. St. Louis, Mo: Mosby Elsevier; 2009:chap 1.