A sex position is a positioning of the bodies that people use to engage in sexual intercourse or other sexual activities. Sexual acts are generally described by the positions the participants adopt in order to perform those acts. Though sexual intercourse generally involves penetration of the body of one person by another, sex positions commonly involve non-penetrative sexual activities.

Three broad and overlapping categories of sexual activity are commonly practiced: vaginal sex, anal sex, and oral sex (mouth-on-genital or mouth-on-anus). Sex acts may also be part of a fourth category, manual sex, which is stimulating the genitals or anus by using fingers or hands. Some acts may include stimulation by a device (sex toy), such as a dildo or vibrator. There are numerous sex positions that participants may adopt in any of these types of sex acts, and some authors have argued that the number of sex positions is essentially limitless.