Oral sex is a sexual practice in which one partner stimulates another's genitals using the mouth, tongue, teeth, lips, or throat. It may occur on its own, as part of foreplay or during intercourse. Twenty-seven percent of men and 19% of women reported having engaged in oral sex according to the 2010 National Survey of Sexual Health and Behavior.
Oral sex is also known as fellatio, oral-genital sex, or cunnilingus. One partner may also refer to oral sex by saying that they "went down on" the other.