Melanin is a biological pigment that can be found in hair, the eyes, the ear, the brain and other parts of the human body. Dermal pigmentation is either dependent on the number, size, composition and distribution of melanocytes or activity of melanogenic enzymes. There are three main types of melanin. Eumelanin, pheomelanin and neuromelanin.

Eumelanin is the most abundant type of melanin in humans. It can be found in two variations. Black eumelanin and brown eumelanin.

Neuromelanin can be found in the medulla, the adrenal gland and pigment bearing neurons (locus coeruleus, substantia nigra, etc.) in the brain.

Pheomelanin is a red-yellow pigment found both in lighter-skinned humans and darker skinned humans. it contains sulphur and is alkali soluble.

Melanin possesses photochemical qualities that makes it an excellent photoprotectant. The protective qualities of melanin rely upon its ability to absorb harmful UV-radiation and transform the solar energy into harmless heat through a process called "ultrafast internal conversion". By this method, melanin can dissipate more than 99.9% of the absorbed UV radiation as heat. This prevents the indirect DNA damage that is responsible for the formation of malignant melanoma and other skin cancers.

Interestingly UV radiation, when it comes in contact with pheomelanin, it possesses the ability of inducing the release of free radicals in the skin, thus intensifying skin damage rather than protecting the skin.