A pimple starts when the pores in the skin become clogged with a type of oil called sebum
, which normally lubricates the skin and hair. Acne is common during puberty
when hormones go into overdrive, causing the skin to overproduce sebum. Because many oil-producing glands are on the forehead, nose, and chin, this area — the T-zone
— is where a person is most prone to pimples.