What is acne? Acne is a disease that affects the skin’s oil glands. The pores in your skin connect to oil glands under the skin. These glands make an oily substance called sebum. The pores connect to the glands by a canal called a follicle. Inside the follicles, oil carries dead skin cells to the surface of the skin. A thin hair also grows through the follicle and out to the skin. When the follicle of a skin gland clogs up, a pimple grows. There are many types of pimples which we will all have experienced to a degree at some time in our lives....