Missionary position in the context of "Tribadism"

Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both. This is also known as vaginal intercourse or vaginal sex. Sexual penetration is an instinctive form of sexual behaviour and psychology among humans. Other forms of penetrative sexual intercourse include anal sex (penetration of the anus by the penis), oral sex (penetration of the mouth by the penis or oral penetration of the female genitalia), fingering (sexual penetration by the fingers) and penetration by use of a dildo (especially a strap-on dildo), and vibrators. These activities involve physical intimacy between two or more people and are usually used among humans solely for physical or emotional pleasure. They can contribute to human bonding.

There are different views on what constitutes sexual intercourse or other sexual activity, which can impact views of sexual health. Although sexual intercourse, particularly the term coitus, generally denotes penile–vaginal penetration and the possibility of creating offspring, it also commonly denotes penetrative oral sex and penile–anal sex, especially the latter. It usually encompasses sexual penetration, while non-penetrative sex has been labeled outercourse, but non-penetrative sex may also be considered sexual intercourse. Sex, often a shorthand for sexual intercourse, can mean any form of sexual activity. Because people can be at risk of contracting sexually transmitted infections during these activities, safer sex practices are recommended by health professionals to reduce transmission risk.

Sexual penetration is the insertion of a body part or other object into a body orifice, such as the mouth, vagina or anus, as part of human sexual activity or sexual behavior in non-human animals.

The term is most commonly used in statute law in the context of proscribing certain sexual activities. Terms such as "sexual intercourse" or "carnal knowledge" are more commonly found in older statutes, while many modern criminal statutes use the term "sexual penetration" because it is a broad term encompassing (unless otherwise qualified) any form of penetrative sexual activity, including digital (i.e., the fingers) or with an object, and may involve only the most minimal penetration. Some jurisdictions refer to some forms of penetration as "acts of indecency", or other terminology.