What is a zit? "Zits" —that's short for pimples or acne. And they're all about hormones. You probably hear that word a lot when you're going through puberty. The reason is that hormones are responsible for a lot of changes going on in your body —the development of breasts, pubic hair, and, yes, zits. Hormones can cause the glands in the pores of your skin to produce more oil than necessary. If this happens, your pores can get blocked. (Kind of like a traffic jam under your skin.) If a pore gets blocked up, the oil glands can get infected with bacteria. When this happens —you get a zit. What is a zit, and what do they look like? Your basic zit is red. There are also whiteheads —zits that are filled with a yellowish or whitish pus —and blackheads. Blackheads look like zits, except they have a black dot on top. Some girls find they get more zits right before their period than at any other time of the month. The reason? Because those hormones are acting up. The good news is that your skin will probably clear up once you've gone through puberty and your hormones calm down. Wondering what is a zit? Get answers and skincare tips from BeingGirl.