Sebum

Sebum is produced by the sebaceous glands in the skin. The Latin meaning of sebum is fat. Sebum comes out of the glands in the skin and coats the hair follicles. You will notice that your hair becomes oily if you leave it unwashed for few days. That is sebum. Through the pore of the hair follicle sebum reaches the surface of the skin. There it mixes with other lipids and sweat and forms a coating on the skin. This coating is called acid mantle. Acid mantle protects the skin against bacteria and keeps the skin hydrated.