The condom has many slang names, including "rubber," "wrapper," and "raincoat." All of these terms refer to a sheath typically made of rubber that is placed over the erect penis before entering the vagina to block the passage of sperm and prevent pregnancy. Aside from abstinence, latex condoms are the most effective method for reducing the risk of infection from the viruses that cause AIDS, other HIV-related illnesses, and other sexually transmitted infections (STIs).
A condom can be used only once and is available at many stores and pharmacies (no prescription required). Some have spermicide added (usually nonoxynol-9 in the United States) to kill sperm, however, spermicide has not been scientifically shown to provide any additional protection over the condom alone. Because they act as a mechanical barrier, condoms prevent direct vaginal contact with semen, infectious genital secretions, and genital lesions and discharges.
Some condoms are pre-lubricated. These lubricants don't provide more birth control or STD protection. Non-oil-based lubricants, such as water or K-Y jelly, can be used with latex or lambskin condoms, but oil-based lubricants, such as petroleum jelly (Vaseline), lotions, or massage or baby oil, should not be used because they can weaken the material. The overall failure rate of condoms is 3% when used according to manufacturer directions.