Birth control refers to something that is used to prevent pregnancy. While there are many different types of birth control, they all fall into one of three different categories: hormonal, barrier, or spermicidal.

Hormonal methods use hormones to prevent ovulation. Without an egg, pregnancy can’t happen. Birth control pills ("the Pill"), Depo-Provera ("the Shot"), NuvaRing ("the Ring"), and Ortho Evra ("the patch") are all hormonal methods of birth control.

Barrier methods put a physical barrier between sperm and egg. Condoms, diaphragms, and cervical caps are all barrier methods of birth control.

Spermicidal methods use a chemical that kills sperm. Spermicidal methods are meant to be used as a back-up method with one of the other methods listed above. By themselves, they’re not very effective. Examples of spermicidal methods include vaginal contraceptive film and vaginal suppositories.

For more information and photos of all the birth control methods, go to the story "An A to Z of Contraception" by Claire Marchetta, 18, Staff Writer.