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 animal sexual behavior.

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.