There are two main types of condoms: condoms used externally and condoms used internally. An external condom (sometimes called a male condom or just a condom) is worn over the penis during sex. It is a thin layer of latex, plastic, synthetic rubber, or natural membrane. Latex condoms provide the best protection against HIV. Plastic (polyurethane) or synthetic rubber condoms are good for people with latex allergies. Note: Plastic condoms break more often than latex condoms. Natural membrane (such as lambskin) condoms have small holes in them and don’t block HIV and other STDs. These should not be used for HIV or STD prevention. An internal condom (sometimes called a female condom) is used in the vagina or anus during sex. It is a thin pouch made of a synthetic latex product called nitrile. HIV can’t travel through the nitrile barrier.