The three layers skin are the fat layer, the dermis and the epidermis. The topmost layer is the epidermis, and the bottom layer is the fat layer, also called the subcutis.
The fatty layer serves as insulation, protection and energy storage for the body. It consists of fat cells in a matrix of fibrous tissue.
The dermis features mainly tissues called collagen, elastin and fibrillin. Nerve endings, sweat glands, hair follicles and blood vessels also live in the dermis.
The epidermis is a thin layer composed mainly of keratinocytes. It protects the body from foreign objects, such as bacteria, viruses and other substances. In the epidermis lies cells called Langerhans, which play a part in protecting the body against infection. Melanocytes also inhabit the epidermis. These cells secrete melanin, a pigment that protects the body from UV rays and gives skin its color.