Melanin is the pigment that absorbs UV light. Melanin is present in human skin and hair, and it serves as a physical barrier that scatters UVR and as an absorbent filter that reduces the penetration of UV through the epidermis. Eumelanin, a type of melanin, is particularly effective at absorbing a wide range of wavelengths of radiation produced by the sun, including higher-energy UV radiation. When UV radiation strikes eumelanin, the pigment absorbs the radiation and mostly transforms the energy into thermal energy, without breaking down, making it a powerful sunscreen that protects against UV damage. Melanin absorbs UVB photons and competes with 7-dehydrocholesterol for them, which influences the effectiveness of vitamin D3 synthesis in the skin.