Epidermis is the outermost layer of the skin. This is the skin layer which is visible to the naked eye. Infact this thin layer of skin is made up of 5 additional layers of skin.
The epidermis has a number of functions. First and foremost it is a protective layer for the entire body. It is water proof and prevents most things from entering the body
The epidermis lacks blood vessels and is nourished from below the skin. It does contain a few specialized cells which protect the skin. Some cells (langerhan cells) kill any bacteria and act as scavenging cells. The melanocytes make melanin and provide the skin color. The merkel cells have specialized nerves but their function remains unknown.
The epidermis is an important organ and is susceptible to injury, burns, cancers, infections and aging. The skin is sometimes the first clue that something may be wrong with an individual.