Condom is a thin rubber or plastic sheath that may be worn over a man's penis during sexual intercourse. It is used as a method of contraception (prevention of conception or pregnancy). Sperm are trapped inside the condom, which is later discarded. As well as helping to prevent conception, condoms can offer protection against sexually transmitted diseases, such as AIDS, chlamydia, gonorrhea, and syphilis. Many health authorities recommend that a condom be used every time sexual intercourse occurs with a person who is infected with HIV (human immunodeficiency virus) or whose infection status is unknown.