So you want to get a beautiful suntan? 

Great!  The process is simple, and occurs the same whether you tan indoors or outdoors.  Tanning occurs in the skin’s outermost layer, the epidermis.  About 5% of the cells in the epidermis are special cells called melanocytes.  Melanocytes produce melanin, a brown pigment that is absorbed by all the surrounding skin cells in the epidermis.  Once absorbed into a skin cell, melanin actually “enshrouds” the cell’s inner material, colouring the cell brown and protecting it from excessive ultraviolet light exposure.

The skin layers absorb ultraviolet light, and our skin produces melanin as a natural and automatic response to UV stimulus.  In years past, it was taught that UVA tanned us, and UVB burned us.  In reality, both UVA and UVB cause tanning and burning—the important factor is that UVA is about a thousand fold less effective than UVB at inducing skin changes, including redness and pigmentation.  UVB may be more dangerous because it was about a thousand fold greater ability to burn than UVA.

THE TANNING PROCESS IN GREATER DETAIL: