人類性行為(英語:Human sexual behaviour),又稱人類性活動(英語:Human sexual activity)、人类性实践(英語:Human sexual practice),是指人類个体任何体验和表達性的活动中所从事的性行为,以及身体对性欲的表现方式、行为、感覺和相互作用。人類所從事的性活動種類廣泛多樣,有的可以獨自完成(如自慰),有的則需與他人一起參與(如性交、非插入式性行為、口交等);而狹義的性行為則是指性交[1]。性活動通常会導致从事者出現性喚起和生理變化,其中一些較為顯著,另一些則否。性活動可能會使从事者的性興趣或性生活品質加強,例如其可作为尋找或吸引伴侣的一种手段(求愛和表現行為)、個体之間的性互動(例如前戲或BDSM)[2]。
性行為在社會性動物的相互影響中發揮了很大作用。進化生物學家瓊·拉夫加登(英语:Joan Roughgarden)在其著作《自然界和人类的多樣性、性別和性》(Diversity, Gender, and Sexuality in Nature and People)中指出此一道理除了人類,还適用於其他社會性動物身上。她在書中探討了性行為的目的,並證明了其具有多種功用,包括維持配偶之間和團體內的紐帶、解決糾紛、繁殖下一代[9]。
Daniel L. Schacter, Daniel T. Gilbert, Daniel M. Wegner. Psychology. Macmillan. 2010: 335–336 [10 November 2012]. ISBN 1429237198. (原始内容存档于2020-09-17).
Richard M. Lerner; Laurence Steinberg. Handbook of Adolescent Psychology. John Wiley & Sons. 2004: 193–196 [2013-04-29]. ISBN 0471690449. (原始内容存档于2013-10-15). When researchers use the term sex, they nearly always mean sexual intercourse – more specifically, penile–vaginal intercourse... The widespread, unquestioned equation of penile–vaginal intercourse with sex reflects a failure to examine systematically 'whether the respondent's understanding of the question matches what the researcher had in mind.'
Fedwa Malti-Douglas. Encyclopedia of Sex and Gender: A-C. Macmillan Reference. 2007: 308. ISBN 0028659619. Sexual intercourse. [T]he term coitus indicates a specific act of sexual intercourse that also is known as coition or copulation. This 'coming together' is generally understood in heteronormative terms as the penetration of a woman's vagina by a man's penis.
Irving B. Weiner; W. Edward Craighead. The Corsini Encyclopedia of Psychology4. John Wiley & Sons. 2010: 1577 [2013-08-21]. ISBN 0470170239. (原始内容存档于2013-12-31). Human sexual intercourse, or coitus, is one of the most common sexual outlets among adults. Sexual intercourse generally refers to penile penetration of the vagina...
Clint E. Bruess; Elizabeth Schroeder. Sexuality Education Theory and Practice. Jones & Bartlett Publishers. 2013: 152 [2014-12-05]. ISBN 1449649289. (原始内容存档于2015-03-26). Vaginal sex is defined as when a penis or sex toy is inserted into a vagina for pleasure. In many cultures around the world, vaginal sex is what is usually implied when people refer to 'having sex' or 'sexual intercourse.' It is the most frequently studied behavior and is often the focus of sexuality education programming for youth.
Anal Sex Safety and Health Concerns. WebMD. [2013-08-19]. (原始内容存档于2017-11-12). Often referred to simply as anal sex, anal intercourse is sexual activity that involves inserting the penis into the anus.
Chalkley A. J.; Powell G. E. The clinical description of forty-eight cases of sexual fetishism. British Journal of Psychiatry. 1983, 142: 292–295. doi:10.1192/bjp.142.3.292.
Moore, Andrew. Hedonism. Zalta, Edward N. (编). The Stanford Encyclopedia of Philosophy Winter 2018. Metaphysics Research Lab, Stanford University. 2018 [2018-11-08]. (原始内容存档于2019-05-26).
Assault, Black's Law Dictionary, 8th Edition. See also Ibbs v The Queen, High Court of Australia, 61 ALJR 525, 1987 WL 714908 (sexual assault defined as sexual penetration without consent); Sexual Offences Act 2003 Chapter 42 s 3 Sexual assault (United Kingdom), (sexual assault defined as sexual contact without consent), and Chase v. R. 1987 CarswellNB 25 (Supreme Court of Canada) (sexual assault defined as force without consent of a sexual nature)