Oral sex consists of all sexual activities that involve the use of the mouth which may include use of the tongue teeth and throat to stimulate genitalia. Cunnilingus refers to oral sex performed on a woman and fellatio refers to oral sex performed on a man. Analingus refers to oral stimulation of a persons anus.

People may engage in oral sex as part of foreplay before intercourse or during or following intercourse. It may also be performed for its own sake.

Oral sex is practiced in both heterosexual and homosexual relationships. In heterosexual relationships oral sex can be a method of contraception and may be chosen as an alternative to intercourse for this reason.

Facesitting is a form of oral sex in which the receiver sits on the givers face and pushes into it with his or her genitals. Oral sex can be performed by both partners at the same time in the so-called "sixty-nine" position.

Spitting and/or swallowing of the ejaculatory fluids may cause different sexual stimulations. Also eye contact during fellatio or cunnilingus may be very stimulating and more pleasurable because it acknowledges that a real person is performing oral sex not a machine or sex toy. Autofellatio is a possible but rare variant autocunnilingus may also be possible for women with extremely flexible spines.

There are many words describing oral sex including euphemisms and slang. Like all aspects of sexuality there exists a very large number of variations on a theme making it essentially impossible to compose a comprehensive list.

Giving head - A common slang term for giving oral sex to either a man or woman is "giving head" from the term "head job" (in contrast to "hand job" manual stimulation). A play on the slang term "head" resulted in the slang term "brains" or "brain salad surgery" "domes" or "getting domes."

Cunnilingus is also sometimes referred to as "muff diving" "eating out" or "poon-job" a slang term and a cunnilingus variant of "blow job" (see the section of Fellatio above) where "poon" is short for poontang or punani.

Additionally in lesbian culture several common slang terms used are "carpet munching" "giving lip" "lip service" or "tipping the velvet".

Additional slang terms for oral sex include "going down on" (female and male) "licking out" (female) "blow job" (male) "dome" (female and male) "sucking off" (male) "rolling cigars" (male recipient) "lolly-gagging" (gay male-on-male) and "gaining knowledge" (male recipient).