The skin, the largest sized organ in the human body, is composed of two layers: the epidermis and the dermis. Underneath the dermis lies the subcutis, which consists mainly of fat cells.
Epidermis—The epidermis forms the outer layer. At the base of this layer, the cells continuously divide, forming new cells. As cells are made, they are pushed toward the surface by the newer cells underneath them, and finally reach the keratinous layer. Finally, the outermost cells in thekeratinous layer are shed.

Dermis—The dermis forms the layer below the epidermis and is thicker than the epidermis. The dermis is especially made up of collagen and elastin fibers. It also contains blood vessels, nerves, sensory organs, sebaceous glands, sweat glands, and hair follicles.

Subcutis—This layer lies beneath the dermis and consists of fat cells.