The skin is the largest organ of the human body. It has three layers: epidermis, dermis, and hypodermis.
The epidermis is the outermost layer. It is composed of keratinocytes, a type of epithelial cell that produces keratin. The compact nature of the epithelial cells of the epidermis makes the skin waterproof. Melanocytes are also found in this layer and produce melanin, or skin pigment. The epidermis function as protection against UV rays.
The dermis is the inner thicker layer that is mostly composed of connective tissue and connected to the epidermis by collagen fibers. The structures found in this layer are the hair follicle, hair root, sebaceous gland, and sweat gland. The dermis function is to excrete excess oils and waste out of the body through the production of sweat and production of vitamin D with specialized cells found in this skin layer.
The hypodermis is the innermost layer that is composed of adipose tissue. It functions as a cushion between the muscles and the skin.