Your skin protects your body from heat, injury, and infection. It also protects your body from damage caused by ultraviolet (UV) radiation (such as from the sun or sunlamps). Your skin stores water and fat. It helps control body heat. Also, your skin makes vitamin D.
Epidermis: The epidermis is the top layer of your skin. It's mostly made of flat cells called squamous cells. Below the squamous cells deeper in the epidermis are round cells called basal cells. Cells called melanocytes are scattered among the basal cells. They are in the deepest part of the epidermis. Melanocytes make the pigment (color) found in skin. When skin is exposed to UV radiation, melanocytes make more pigment, causing the skin to darken, or tan. Dermis: The dermis is the layer under the epidermis. The dermis contains many types of cells and structures, such as blood vessels, lymph vessels, and glands. Some of these glands make sweat, which helps cool your body. Other glands make sebum. Sebum is an oily substance that helps keep your skin from drying out. Sweat and sebum reach the surface of your skin through tiny openings called pores.