Your skin is made up of two layers. The top part of the skin is actually made up of dead cells that get rubbed off constantly as new skin cells are pushed up to replace them. Under this is the part of the skin that contains blood vessels, nerve endings, and hair roots. You should always protect your skin from too much sun.
Why you have dead skin cells
why too much sun is bad for you
What the layers of skin are
Where the blood vessels are