How does skin tan?
Tanning is the way in which the skin protects itself from the sun's ultraviolet rays. This occurs as follows: in the dermis, which is the middle layer of the skin, there are cells called melanocytes that secrete a substance called melanin, which in turn pigments the skin. When the sun's UV rays reach the skin, melanin surrounds the cells as a protective mechanism and proceeds to absorb these rays. When melanin comes into contact with UV radiation, it oxidizes and thus causes the skin to turn a darker shade.
