Acne is a skin disease consisting of blemishes that can occur on your face neck chest shoulders and back. Acne is very common during the teen years but it can affect you during adulthood as well. To keep your hair and skin well lubricated your body depends on sebaceous glands which set just under your skin. These glands secrete an oily substance called sebum which coats your skin and hair to prevent them from drying out sebum travels up hair follicles and out through your pores onto the surface of your skin. Your hair follicles routinely shed dead skin cells that sebum carries out of your body.