The diaphragm, cervical cap, condom, and spermicidal products are all barrier forms of birth control, designed to block sperm from entering the uterus.
Barrier methods prevent pregnancy by creating an actual, physical barrier between the sperm and the egg, or prevent some sexually transmitted infections by preventing the exchange of body fluids during sexual activity. Barrier methods to prevent pregnancy include the condom, intrauterine device (IUD), diaphragm, cervical cap, and shield. Condoms are the only current barrier method for preventing sexually transmitted infections, including HIV.