How do condoms prevent STD transmission?

STDs are transmitted by direct contact between bodily fluids (semen, vaginal fluids, blood, saliva, etc.) or through skin-to-skin contact, depending on the type of STD. A https://www.cdc.gov/condomeffectiveness/" target="_blank" rel="nofollow">condom prevents this sort of contact from being made. Usually made of latex, a condom covers the penis to prevent direct contact. Dental dams also serve this purpose in oral sex.

While condoms and dental dams considerably lower the risk of STD transmission, no method is perfect. It’s important to know how to use these barriers correctly to have the highest degree of protection.