There are two main skin layers:

• The outer layer (epidermis)
• The inner layer (dermis)

The skin cells (melanocytes) that develop into melanoma usually are found in the epidermis.

The bottom layer shown in the picture (subcutaneous layer) is not really part of the skin. It is a layer of connective tissue, fat cells, blood vessels, and nerves. This layer lies between the skin and the structures under it, such as muscles.

Skin depth varies depending on location. It is thin on the neck and thick on the soles of the feet.