Editing Sexual intercourse (section)

==Behaviors==
{{See also|Human sexual activity|Human sexuality}}

===Definitions===
[[File:Édouard-Henri Avril (18).jpg|thumb|19th-century [[Eroticism|erotic]] interpretation of Roman emperor [[Hadrian]] and [[Antinous]] engaged in anal intercourse, by [[Édouard-Henri Avril]]]]
<!-- NOTE: This section was titled "Etymology and definitions." As the etymology material is defining sexual intercourse, and there is little material on the etymology, there appears to be no need to have separate sections. Per MOS:PARAGRAPHS, "Short paragraphs and single sentences generally do not warrant their own subheading." The heading was subsequently shortened to "Definitions" and added as a subsection of the Behaviors section (since it includes researchers' views and general views on definitions and behaviors).-->

''Sexual intercourse'' may be called ''coitus'', ''copulation'', ''coition'', or ''intercourse''. ''Coitus'' is derived from the [[Latin]] word ''coitio'' or ''coire'', meaning "a coming together or joining together" or "to go together", and is known under different ancient Latin names for a variety of sexual activities, but usually denotes penile–vaginal penetration.<ref name="Coitus">
* {{cite dictionary|title=Coitus| date=August 14, 2024| dictionary=[[Merriam-Webster]]|url=http://www.merriam-webster.com/dictionary/coitus}}
* {{cite book| author = Fedwa Malti-Douglas |author-link=Fedwa Malti-Douglas |title = Encyclopedia of Sex and Gender: A-C |publisher = [[Macmillan Publishers|Macmillan Reference]] | year = 2007 | page = 308 |isbn = 978-0-02-865961-9 |quote=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.}}
* {{cite book|title = The Encyclopedia of Mental Health | publisher = [[Infobase Publishing]] | year = 2008 | page = 111|isbn = 978-0-8160-6454-0| url = https://books.google.com/books?id=tTFYIh-HcYYC&pg=PA111|author1=Ada P. Kahn |author2=Jan Fawcett }}
</ref> This is often called [[vaginal intercourse]] or ''vaginal sex.''<ref name="Alters"/><ref name="Carroll">See [https://books.google.com/books?id=gU3SZSh-eXsC&pg=PT334 page 302] for orgasm information, and [https://books.google.com/books?id=gU3SZSh-eXsC&pg=PT316 pages 285–286] for definitions, prevalence and length of sexual intercourse. {{cite book |vauthors=Carroll JL| title = Discovery Series: Human Sexuality| edition = 1st | publisher = [[Cengage Learning]]|pages=656 pages| isbn = 978-1-111-84189-8|year=2012|url=https://books.google.com/books?id=gU3SZSh-eXsC}}</ref> ''Vaginal sex,'' and less often ''vaginal intercourse'', may also denote any vaginal sexual activity, particularly if [[Sexual penetration|penetrative]], including [[lesbian sexual practices|sexual activity between lesbian couples]].<ref name="Harvey">{{cite book|vauthors = Milkman HB, Wanberg KW | title = Pathways to Self-Discovery and Change: Criminal Conduct and Substance Abuse Treatment for Adolescents | publisher = [[SAGE Publications|SAGE]] | year = 2004 | pages = 254–255|isbn = 978-1-4129-0614-2| url =https://books.google.com/books?id=2ovqg5jfsN0C&pg=PA254}}</ref><ref name="Kinetics">{{cite book| vauthors = Kinetics H | title = Health and Wellness for Life| publisher = Human Kinetics | year = 2009 | page = 207|isbn = 978-0-7360-6850-5| url =https://books.google.com/books?id=2GZ7N4wOeGYC&pg=PA207}}</ref> ''Copulation'', by contrast, more often denotes the [[mating]] process, especially for non-human animals; it can mean a variety of sexual activities between opposite-sex or [[same-sex pairings]],<ref name="Barrows">{{cite book| vauthors = Barrows EM| title = Animal Behavior Desk Reference: A Dictionary of Animal Behavior, Ecology, and Evolution | publisher = [[Taylor & Francis]] | year = 2011 | pages = 122–124 |isbn = 978-1-4398-3651-4 | url=https://books.google.com/books?id=2vf7ZbLENzEC&pg=PA122}}</ref> but generally means the [[Sexual reproduction|sexually reproductive]] act of transferring [[Spermatozoon|sperm]] from a male to a female or sexual procreation between a man and a woman.<ref name="Barrows"/><ref name="Copulation1">{{cite web|title=Copulation|publisher=[[Dorland's medical reference works|Dorland's Medical Dictionary for Health Consumers]], 2007/[[TheFreeDictionary.com]] for various dictionary definitions|access-date=September 6, 2012|url=http://medical-dictionary.thefreedictionary.com/copulation}}</ref><ref name="Copulation2">{{cite web|title=Copulation|publisher=[[The American Heritage Dictionary of the English Language]], Fifth Edition|year=2011|access-date=August 23, 2013|url=http://ahdictionary.com/word/search.html?q=Copulation}}</ref>

Although ''sex'' and ''having sex'' also most commonly denote penile–vaginal intercourse,<ref name="Most common2">
* {{cite book| author = Ken Plummer | author-link = Ken Plummer (sociologist) | title = Modern Homosexualities: Fragments of Lesbian and Gay Experiences | publisher = [[Routledge]] | year = 2002 | pages = 187–191 | access-date = August 24, 2013|isbn =978-1-134-92242-0 | url=https://books.google.com/books?id=OSO3q4XEfz4C&pg=PA189|quote=[S]ome sexual practices are regarded as inherently better (normal, natural, more satisfying) than others, with vaginal intercourse privileged as the 'Real Thing.' Such beliefs, influenced by views about sex as ultimately a reproductive function, continue to be perpetuated through discourses on sex despite a number of important contradictions.}}
* {{cite book | title = Handbook of Adolescent Psychology | publisher = [[John Wiley & Sons]] | year = 2004 | pages = 193–196 |isbn = 978-0-471-69044-3| url = https://books.google.com/books?id=_wXasY1HyAYC&pg=PA193|quote=When researchers use the term ''sex'', they nearly always mean sexual intercourse&nbsp;– 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.'| author = Richard M. Lerner| author-link = Richard M. Lerner| author2 = Laurence Steinberg| author2-link = Laurence Steinberg}}
* See [https://books.google.com/books?id=6qNCeI2AcY4C&pg=PT11 page 11 onwards] and [https://books.google.com/books?id=pXXZn_qSoDoC&pg=PA48 pages 47–49] for views on what constitutes virginity loss and therefore sexual intercourse or other sexual activity; source discusses how gay and lesbian individuals define virginity loss, and how the majority of researchers and heterosexuals define virginity loss/"technical virginity" by whether a person has engaged in penile–vaginal sex. {{Cite book|author=Laura M. Carpenter|title=Virginity Lost: An Intimate Portrait of First Sexual Experiences|publisher=[[New York University|NYU Press]]|year = 2005|pages=295 pages |isbn=978-0-8147-1652-6|url=https://books.google.com/books?id=pXXZn_qSoDoC}}
* {{cite book| author = Fedwa Malti-Douglas|title = Encyclopedia of Sex and Gender: A-C| publisher = [[Macmillan Publishers|Macmillan Reference]] | year = 2007 | page = 308 |isbn = 978-0-02-865961-9|quote=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.}}
* {{cite book |author=Irving B. Weiner |author1-link=Irving B. Weiner |author2=W. Edward Craighead |title=The Corsini Encyclopedia of Psychology |volume=4 |publisher=[[John Wiley & Sons]] |year=2010 |page=1577 |access-date=August 21, 2013 |isbn=978-0-470-17023-6 |url=https://books.google.com/books?id=pUSG1BONmekC&pg=PA1577 |quote=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.}}
* {{cite book| author = Clint E. Bruess| author2 = Elizabeth Schroeder|title = Sexuality Education Theory and Practice| publisher = [[Jones & Bartlett Publishers]] | year = 2013 | page = 152 |isbn = 978-1-4496-4928-9| url =https://books.google.com/books?id=WWFW6-kkAVoC&pg=PA152|quote=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.}}</ref> ''sex'' can be significantly broad in its meaning and may cover any penetrative or [[non-penetrative sex|non-penetrative]] sexual activity between two or more people.<ref name="WHO, Sex"/> The [[World Health Organization]] (WHO) states that non-English languages and cultures use different words for sexual activity, "with slightly different meanings".<ref name="WHO, Sex"/> Various [[vulgarisms]], [[slang]], and [[euphemism]]s are used for sexual intercourse or other sexual activity, such as ''[[fuck]]'', ''screw'', ''shag'', and the phrase "sleep together".<ref name="Fuck">{{cite dictionary|title=Fuck|dictionary=[[Merriam-Webster]]|access-date=March 30, 2013|url=http://www.merriam-webster.com/dictionary/fuck}}</ref><ref>{{cite dictionary|title=Shag|dictionary=[[Merriam-Webster]]|access-date=March 30, 2013|url=http://www.merriam-webster.com/dictionary/shag}}</ref><ref name="Sleep together">{{cite web|title=Sleep together|publisher=[[TheFreeDictionary.com]]|access-date=March 30, 2013|url=http://www.thefreedictionary.com/sleep+together}}</ref> The laws of some countries use the euphemism, [[carnal knowledge]]. Penetration of the vagina by the [[Erection|erect]] penis is additionally known as ''intromission'', or by the Latin name ''[[wikt:immissio#Latin|immissio]] [[wikt:penis#Latin|penis]]'' (Latin for "insertion of the penis").<ref name="Intromission">{{cite dictionary|title=Intromission| dictionary=[[Merriam-Webster]]|access-date=December 26, 2012|url=http://www.merriam-webster.com/dictionary/intromission}}</ref> The age of first sexual intercourse is called ''sexarche''.<ref>{{cite web |title=sexarche - oi |publisher=Oxford University Press |work=Concise Medical Dictionary |url=http://oxfordindex.oup.com/view/10.1093/oi/authority.20110803100457655 |access-date=July 4, 2017 |archive-date=June 24, 2019 |archive-url=https://web.archive.org/web/20190624230226/https://oxfordindex.oup.com/view/10.1093/oi/authority.20110803100457655 |url-status=dead}}</ref><ref name="LaraAbdo2016">{{cite journal|vauthors=Lara LS, Abdo CH|title=Age at Time of Initial Sexual Intercourse and Health of Adolescent Girls|journal=Journal of Pediatric and Adolescent Gynecology|volume=29|issue=5|year=2016|pages=417–423|issn=1083-3188|doi=10.1016/j.jpag.2015.11.012|pmid=26655691}}</ref>

Vaginal, anal and oral sex are recognized as sexual intercourse more often than other sexual behaviors.<ref name="Most common forms">
* {{cite web| title= Sexual Intercourse | publisher=[[Discovery Channel|Discovery.com]]| access-date=January 12, 2008 | url=http://health.discovery.com/centers/sex/sexpedia/intercourse.html |archive-url =https://web.archive.org/web/20080822040701/http://health.discovery.com/centers/sex/sexpedia/intercourse.html|archive-date = August 22, 2008}}
* {{cite book|author = Harvey B. Milkman|author2 = Kenneth W. Wanberg | title = Pathways to Self-Discovery and Change: Criminal Conduct and Substance Abuse Treatment for Adolescents | publisher = [[SAGE Publications|SAGE]] | year = 2004 | pages = 254–255|isbn = 978-1-4129-0614-2| url =https://books.google.com/books?id=2ovqg5jfsN0C&pg=PA254}}
* {{cite book| author = Nancy W. Denney| author2 = David Quadagno | title = Human Sexuality | publisher = [[Mosby-Year Book]] | year = 2008 | page = 273|isbn = 978-0-8016-6374-1}}</ref> Sexual activity that does not involve penile-vaginal sex or other sexual penetration might be used to retain virginity (sometimes called [[technical virginity]]) or labeled ''outercourse''.<ref name="Technical virginity">
* See [https://books.google.com/books?id=6qNCeI2AcY4C&pg=PT11 page 11 onwards] and [https://books.google.com/books?id=pXXZn_qSoDoC&pg=PA48 pages 47–49] for views on what constitutes virginity loss and therefore sexual intercourse or other sexual activity; source discusses how gay and lesbian individuals define virginity loss, and how the majority of researchers and heterosexuals define virginity loss/"technical virginity" by whether a person has engaged in penile–vaginal sex. {{Cite book|author=Laura M. Carpenter|title=Virginity Lost: An Intimate Portrait of First Sexual Experiences|publisher=[[New York University|NYU Press]]|year = 2005|access-date=October 9, 2011|pages=295 pages |isbn=978-0-8147-1652-6|url=https://books.google.com/books?id=pXXZn_qSoDoC}}
* {{Cite book|author1=Bryan Strong |author2=Christine DeVault |author3=Theodore F. Cohen |author1-link=Bryan Strong |title=The Marriage and Family Experience: Intimate Relationship in a Changing Society| publisher = [[Cengage Learning]]|year = 2010|page = 186| isbn = 978-0-534-62425-5|url=https://books.google.com/books?id=qjvoSOMB5JMC&pg=PA186|quote=Most people agree that we maintain virginity as long as we refrain from sexual (vaginal) intercourse. ...But occasionally we hear people speak of 'technical virginity' ... Other research, especially research looking into virginity loss, reports that 35% of virgins, defined as people who have never engaged in vaginal intercourse, have nonetheless engaged in one or more other forms of heterosexual activity (e.g. oral sex, anal sex, or mutual masturbation). ... Data indicate that 'a very significant proportion of teens ha[ve] had experience with oral sex, even if they haven't had sexual intercourse, and may think of themselves as virgins'.}}
* {{cite book | title = Our Sexuality | publisher = [[Cengage Learning]] | year = 2010 | pages = 286–289 |isbn = 978-0-495-81294-4| url = https://books.google.com/books?id=MpRnPtmdRVwC&pg=PA286|quote=Noncoital forms of sexual intimacy, which have been called outercourse, can be a viable form of birth control. Outercourse includes all avenues of sexual intimacy other than penile–vaginal intercourse, including kissing, touching, mutual masturbation, and oral and anal sex. |author1=Robert Crooks |author2=Karla Baur }}
* {{cite book|vauthors=UD, TK|title =Promoting Healthy Behaviour: A Practical Guide | publisher = [[Routledge]] | year = 2014 | pages = 243–248|isbn =978-1-317-81887-8| url =https://books.google.com/books?id=63XMAgAAQBAJ&pg=PA243}}</ref> One reason virginity loss is often based on penile–vaginal intercourse is because heterosexual couples may engage in anal or oral sex as a way of being sexually active while maintaining that they are virgins since they have not engaged in the reproductive act of coitus.<ref name="Technical virginity 2">
* See [https://books.google.com/books?id=6qNCeI2AcY4C&pg=PT11 page 11 onwards] and [https://books.google.com/books?id=pXXZn_qSoDoC&pg=PA48 pages 47–49] for views on what constitutes virginity loss and therefore sexual intercourse or other sexual activity; source discusses how gay and lesbian individuals define virginity loss, and how the majority of researchers and heterosexuals define virginity loss/"technical virginity" by whether a person has engaged in penile–vaginal sex. {{Cite book|author=Laura M. Carpenter|title=Virginity Lost: An Intimate Portrait of First Sexual Experiences|publisher=[[New York University|NYU Press]]|year = 2005|access-date=October 9, 2011|pages=295 pages |isbn=978-0-8147-1652-6|url=https://books.google.com/books?id=pXXZn_qSoDoC}}
* {{Cite book|author1=Bryan Strong |author2=Christine DeVault |author3=Theodore F. Cohen |author1-link=Bryan Strong |title=The Marriage and Family Experience: Intimate Relationship in a Changing Society| publisher = [[Cengage Learning]]|year = 2010|page = 186| isbn = 978-0-534-62425-5|url=https://books.google.com/books?id=qjvoSOMB5JMC&pg=PA186|quote=Most people agree that we maintain virginity as long as we refrain from sexual (vaginal) intercourse. ...But occasionally we hear people speak of 'technical virginity' ... Other research, especially research looking into virginity loss, reports that 35% of virgins, defined as people who have never engaged in vaginal intercourse, have nonetheless engaged in one or more other forms of heterosexual activity (e.g. oral sex, anal sex, or mutual masturbation). ... Data indicate that 'a very significant proportion of teens ha[ve] had experience with oral sex, even if they haven't had sexual intercourse, and may think of themselves as virgins'.}}
* {{cite book|vauthors=UD, TK|title =Promoting Healthy Behaviour: A Practical Guide | publisher = [[Routledge]] | year = 2014 | pages = 243–248|isbn =978-1-317-81887-8| url = https://books.google.com/books?id=63XMAgAAQBAJ&pg=PA243}}</ref> Some [[gay men]] consider [[frot]] or oral sex as a way of maintaining their virginities, with penile-anal penetration used as sexual intercourse and for virginity loss, while other gay men may consider frot or oral sex as their main forms of sexual activity.<ref name="Carpenter"/><ref name="Virgin">{{cite magazine|vauthors=Gross MJ|title = Like a Virgin|id = 0001-8996|magazine=[[The Advocate (LGBT magazine)|The Advocate]]|publisher=[[Here Media]]|year=2003|pages=44–45|access-date=March 13, 2011|url=https://books.google.com/books?id=eWQEAAAAMBAJ&pg=PA44}}</ref><ref name="Dolby">{{cite magazine|vauthors=Dolby T|title=Why Some Gay Men Don't Go All The Way|magazine=[[Out (magazine)|Out]]|date=February 2004|access-date=February 12, 2011|pages=76–77|publisher=Here|url=https://books.google.com/books?id=jmIEAAAAMBAJ&pg=PA76}}</ref> Lesbians may categorize oral sex or [[Fingering (sexual act)|fingering]] as sexual intercourse and subsequently an act of virginity loss,<ref name="Carpenter">See [https://books.google.com/books?id=6qNCeI2AcY4C&pg=PT11 page 11 onwards] and [https://books.google.com/books?id=pXXZn_qSoDoC&pg=PA48 pages 47–49] for views on what constitutes virginity loss and therefore sexual intercourse or other sexual activity; source discusses how gay and lesbian individuals define virginity loss, and how the majority of researchers and heterosexuals define virginity loss/"technical virginity" by whether a person has engaged in penile–vaginal sex. {{Cite book|vauthors=Carpenter LM|title=Virginity Lost: An Intimate Portrait of First Sexual Experiences|publisher=[[New York University|NYU Press]]|year = 2005|pages=295 pages |isbn=978-0-8147-1652-6|url=https://books.google.com/books?id=pXXZn_qSoDoC}}</ref><ref name="Lerner">{{cite book|vauthors=Lerner RM, Steinberg L|title = Handbook of Adolescent Psychology | publisher = [[John Wiley & Sons]] | year = 2004 | pages = 193–196 |isbn = 978-0-471-69044-3| url = https://books.google.com/books?id=_wXasY1HyAYC&pg=PA193|quote=When researchers use the term ''sex'', they nearly always mean sexual intercourse&nbsp;– 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.'}}</ref> or [[tribadism]] as a primary form of sexual activity.<ref name="Greenberg">{{cite book|vauthors=Greenberg JS, Bruess CE, Conklin SC|title= Exploring the Dimensions of Human Sexuality|id = 9780763741488|publisher=[[Jones & Bartlett Learning]]|year=2007|page=429|url=https://books.google.com/books?id=ZdYh_iFZvbkC&pg=PA429|isbn =978-0-7637-4148-8}}</ref><ref name="Weiten3">{{cite book|vauthors=Weiten W, Dunn DS, Hammer EY|title=Psychology Applied to Modern Life: Adjustment in the 21st Century|id =1305968476|publisher=[[Cengage Learning]]|year=2016|page=349|isbn =978-0-7637-4148-8|access-date=December 27, 2017|url=https://books.google.com/books?id=09S5DQAAQBAJ&pg=PA349}}</ref>

Researchers commonly use ''sexual intercourse'' to denote penile–vaginal intercourse while using specific words, such as ''anal sex'' or ''oral sex'', for other sexual behaviors.<ref name="Researchers">
* {{cite book|title= Exploring Human Sexuality: Making Healthy Decisions|id = 9780763741488|publisher=[[Allyn & Bacon]]|year=2003|page=229|isbn =978-0-205-38059-6|author1=Richard D. McAnulty |author2=M. Michele Burnette }}
* {{cite book | title = Handbook of Adolescent Psychology | publisher = [[John Wiley & Sons]] | year = 2004 | pages = 193–196 |isbn = 978-0-471-69044-3| url = https://books.google.com/books?id=_wXasY1HyAYC&pg=PA193|quote=When researchers use the term ''sex'', they nearly always mean sexual intercourse&nbsp;– 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.'| author = Richard M. Lerner| author-link = Richard M. Lerner| author2 = Laurence Steinberg| author2-link = Laurence Steinberg}}
* See [https://books.google.com/books?id=6qNCeI2AcY4C&pg=PT11 page 11 onwards] and [https://books.google.com/books?id=pXXZn_qSoDoC&pg=PA48 pages 47–49] for views on what constitutes virginity loss and therefore sexual intercourse or other sexual activity; source discusses how gay and lesbian individuals define virginity loss, and how the majority of researchers and heterosexuals define virginity loss/"technical virginity" by whether a person has engaged in penile–vaginal sex. {{Cite book|author=Laura M. Carpenter|title=Virginity Lost: An Intimate Portrait of First Sexual Experiences|publisher=[[New York University|NYU Press]]|year = 2005|access-date=October 9, 2011|pages=295 pages |isbn=978-0-8147-1652-6|url=https://books.google.com/books?id=pXXZn_qSoDoC}}
* {{cite book | title = Handbook of Health Psychology | edition = 2nd|publisher = [[Psychology Press]] | year = 2012 | pages = 259–260 |isbn = 978-0-8058-6461-8| url =https://books.google.com/books?id=FZOjc8ouMlsC&pg=PA259|author1=Andrew Baum |author2=Tracey A. A. Revenson |author3=Jerome Singer }}
* {{cite book|vauthors=Aggleton P, Ball A, Mane P|title = Sex, Drugs and Young People: International Perspectives| publisher = [[Routledge]] | year = 2013 | page = 74|isbn =978-1-134-33310-3| url =https://books.google.com/books?id=HWcnAAAAQBAJ|quote=Having started with a discussion of penile-vaginal intercourse as the act that designates sexual initiation, as defined in most studies, we would like to undercut that position by stressing the need to define sex more broadly.}}</ref> Scholars [[Richard M. Lerner]] and [[Laurence Steinberg]] state that researchers also "rarely disclose" how they conceptualize sex "or even whether they resolved potential discrepancies" in conceptualizations of sex.<ref name="Lerner"/> Lerner and Steinberg attribute researchers' focus on penile–vaginal sex to "the larger culture's preoccupation with this form of sexual activity", and have expressed concern that the "widespread, unquestioned equation of penile–vaginal intercourse with sex reflects a failure to examine systematically 'whether the respondent's understanding of the question [about sexual activity] matches what the researcher had in mind'".<ref name="Lerner"/> This focus can also relegate other forms of mutual sexual activity to [[foreplay]] or contribute to them not being regarded as "real sex", and limits the meaning of [[rape]].<ref name="Baum">{{cite book |vauthors=McClelland SI |veditors=Baum A, Revenson TA, Singer J |chapter=Measuring Sexual Quality of Life: Ten Recommendations for Health Psychologists |title=Handbook of Health Psychology |edition=2nd |publisher=[[Psychology Press]] |year=2012 |pages=259–260 |access-date=April 30, 2013 |isbn=978-0-8058-6461-8 |chapter-url=https://books.google.com/books?id=FZOjc8ouMlsC&pg=PA259}}</ref><ref name="Kalbfleisch">{{cite book|vauthors= Kalbfleisch PJ, Cody MJ| title = Gender Power and Communication in Human Relationships | publisher = [[Routledge]] | year = 2012 | page = 153 | access-date = April 30, 2013|isbn = 978-1-136-48050-8| url = https://books.google.com/books?id=LyMo1RUJwj0C&pg=PA153}}</ref> It may also be that conceptually conflating sexual activity with vaginal intercourse and sexual function hinders and limits information about sexual behavior that [[non-heterosexual]] people may be engaging in, or information about heterosexuals who may be engaging in non–vaginal sexual activity.<ref name="Baum"/>

Studies regarding the meaning of sexual intercourse sometimes come into conflict. While most consider penile–vaginal intercourse to be sex, whether anal or oral intercourse are considered sex is more debatable, with oral sex ranking lowest.<ref name="Upton">{{cite book|vauthors=UD, TK|title =Promoting Healthy Behaviour: A Practical Guide | publisher = [[Routledge]] | year = 2014 | pages = 243–248|isbn =978-1-317-81887-8| url =https://books.google.com/books?id=63XMAgAAQBAJ&pg=PA243}}</ref><ref name="Aggleton 1">{{cite book|vauthors=Aggleton P, Ball A, Mane P|title = Sex, Drugs and Young People: International Perspectives| publisher = [[Routledge]] | year = 2013 | pages = 74–75|isbn =978-1-134-33310-3| url =https://books.google.com/books?id=HWcnAAAAQBAJ}}</ref> The [[Centers for Disease Control and Prevention]] (CDC) stated that "although there are only limited national data about how often adolescents engage in oral sex, some data suggest that many adolescents who engage in oral sex do not consider it to be 'sex'; therefore they may use oral sex as an option to experience sex while still, in their minds, remaining abstinent".<ref name="CDC, oral sex">{{cite web|title=Oral Sex and HIV Risk |date=June 2009 |access-date=August 30, 2013 |publisher=[[Centers for Disease Control and Prevention]] (CDC) |url=https://www.cdc.gov/hiv/resources/Factsheets/pdf/oralsex.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130510210937/http://www.cdc.gov/hiv/resources/Factsheets/pdf/oralsex.pdf |archive-date=May 10, 2013 }}</ref> Upton et al. stated, "It is possible that individuals who engage in oral sex, but do not consider it as 'sex', may not associate the acts with the potential health risks they can bring."<ref name="Upton"/> In other cases, [[condom]] use is a factor, with some men stating that sexual activity involving the protection of a condom is not "real sex" or "the real thing".<ref name="Engel">{{cite book| author = Jonathan Engel | title = The Epidemic: A History of Aids | publisher = [[HarperCollins]] | year = 2009 | page = 242 | access-date = August 30, 2013 |isbn = 978-0-06-185676-1| url = https://books.google.com/books?id=GQud7Hf6oLIC&pg=PT242|quote=Many men simply did not like the feel of condoms, or associated them with emasculation. They say, 'Unless it's flesh on flesh, it's not real sex...}}</ref><ref name="Wekwete">{{cite book| author = Naomi N. Wekwete | title = Adolescent Pregnancy Challenges in the Era of HIV and AIDS: A Case Study of a Selected Rural Area in Zimbabwe | publisher = African Books Collective | year = 2010 | page = 49 | access-date = August 30, 2013 |isbn = 978-99944-55-48-5| url=https://books.google.com/books?id=LB45dcqSOpsC&pg=PA49}}</ref> This view is common among men in Africa,<ref name="Engel"/><ref name="Wekwete"/> where sexual activity involving the protection of a condom is often associated with [[emasculation]] because condoms prevent direct penile–to–skin genital contact.<ref name="Engel"/>

===Stimulation===
Sexual intercourse or other sexual activity can encompass various [[sexually stimulating]] factors ([[Stimulus (physiology)|physiological stimulation]] or [[Stimulus (psychology)|psychological stimulation]]), including different [[sex position]]s (such as the [[missionary position]], the most common human sex position<ref name=":0">[[Julian Monge Najera|Monge-Nájera, J.]], Rodríguez, M., & González, M. I. (2017). [https://revistas.uned.ac.cr/index.php/cuadernos/article/view/1679/1899 Time to deconstruct the concepts of "foreplay" and "intercourse": the real structure of human sexual encounters]. {{ill|Cuadernos de Investigación UNED|es}}, 9(1), 59-64.</ref>) or the use of [[sex toy]]s.<ref name="Weiten, 2008">{{cite book |title=Psychology Applied to Modern Life: Adjustment in the 21st Century |isbn = 978-0-495-55339-7 |publisher=[[Cengage Learning]] |year=2008 |pages=422–423 |access-date=January 5, 2012 |url=https://archive.org/details/isbn_2900495553396/page/422/ |author1=Wayne Weiten |author2=Margaret A. Lloyd |author3=Dana S. Dunn |author4=Elizabeth Yost Hammer |quote=The man-above, or "missionary," position is the most common [[sex position]].}}</ref><ref name="Taormino">{{cite book |last=Taormino |first=Tristan |author-link=Tristan Taormino |title=The Big Book of Sex Toys|publisher=Quiver|year=2009 |access-date=June 9, 2014|page=52|isbn=978-1-59233-355-4|url=https://books.google.com/books?id=Hfly-iMkWRkC&pg=PA52}}</ref> [[Foreplay]] may precede some sexual activities, often leading to [[sexual arousal]] of the partners and resulting in the erection of the [[Human penis|penis]] or [[Vaginal lubrication|natural lubrication]] of the [[vagina]].<ref name="Weiten, 2011">{{cite book|title=Psychology Applied to Modern Life: Adjustment in the 21st Century|isbn =978-1-111-18663-0|publisher=[[Cengage Learning]]|year=2011|pages=384–386|access-date=January 5, 2012|url=https://books.google.com/books?id=CGu96TeAZo0C&pg=PT421 |author1=Wayne Weiten |author2=Dana S. Dunn |author3=Elizabeth Yost Hammer }}</ref> It is also common for people to be as sexually satisfied by being kissed, touched [[eroticism|erotically]], or held as they are during sexual intercourse.<ref name="Alters2">{{cite book| author = Sandra Alters| author2 = Wendy Schiff|title =Essential Concepts for Healthy Living Update|publisher = [[Jones & Bartlett Publishers]] | year = 2011 | page = [https://archive.org/details/essentialconcept00sand_1/page/154 154] | access-date = December 9, 2014 |isbn = 978-1-4496-5374-3| url =https://archive.org/details/essentialconcept00sand_1| url-access = registration}}</ref>

Non-[[primate]] females copulate only when in [[estrus]],<ref name="Pfaus2015"/> but sexual intercourse is possible at any time of the [[menstrual cycle]] for women.<ref name="Reis"/><ref name="Dixson2012">Dixson A.F. (2012) [https://global.oup.com/academic/product/primate-sexuality-9780199676613?cc=fr&lang=en& ''Primate sexuality: Comparative studies of the Prosimians, Monkeys, Apes, and Human Beings.''] Oxford University Press, 2nd edition.</ref> [[Sex pheromones]] facilitate copulatory reflexes in various organisms, but, [[Human sex pheromones|in humans]], the detection of pheromones is impaired and they have only residual effects.<ref name="doty2014">Doty R.L. (2014) [https://www.ncbi.nlm.nih.gov/books/NBK200980/ {{lang|en|Human Pheromones: Do They Exist?}}] in Mucignat-Caretta C. (Ed). ''Neurobiology of Chemical Communication.'' Boca Raton (FL): CRC Press, (19).</ref> Non-primate females put themselves in the crucial [[lordosis position]] and remain motionless, but these motor copulatory reflexes are no longer functional in women.<ref name="Pfaus2015">Pfaus J.G., Flanagan-Cato L.M., Blaustein J.D. (2015) Female sexual behavior. in Plant T., Zeleznik A. (Eds). Knobil and Neill's Physiology of Reproduction. Academic Press, 4th edition</ref>

[[File:Édouard-Henri Avril (14).jpg|thumb|left|[[Édouard-Henri Avril]] depiction of a [[woman on top position]], a position that is more likely to stimulate the clitoris<ref name="Roberts">{{cite book|title=Sex|publisher=Lotus Press|year=2006|page=145|isbn = 978-81-89093-59-4|access-date=August 17, 2012|url=https://books.google.com/books?id=zDS9kC03x2IC&pg=PA145|author=Keath Roberts}}</ref>]]
During coitus, the partners orient their hips to allow the penis to move back and forth in the vagina to cause friction, typically without fully removing the penis. In this way, they stimulate themselves and each other, often continuing until orgasm in either or both partners is achieved.<ref name="Kahn, Fawcett"/><ref name="Starr2">{{cite book|title=Human Biology|isbn =978-0-495-56181-1|publisher=[[Cengage Learning]]|year=2008|page=314|access-date=April 30, 2013|url=https://books.google.com/books?id=09reWGhFDqUC&pg=PA314|author1=Cecie Starr |author2=Beverly McMillan }}</ref>

For human females, stimulation of the [[clitoris]] plays a significant role in sexual activity; 70–80% of women require direct clitoral stimulation to achieve orgasm,<ref name="Flaherty">{{cite book|title=Psychiatry: Diagnosis & therapy. A Lange clinical manual|isbn=978-0-8385-1267-8|publisher=[[Appleton & Lange]] (Original from Northwestern University)|year=1993|pages=[https://archive.org/details/psychiatrydiagno00flah/page/544 544 pages]|url=https://archive.org/details/psychiatrydiagno00flah/page/544|quote=The amount of time of sexual arousal needed to reach orgasm is variable&nbsp;— and usually much longer&nbsp;— in women than in men; thus, only 20–30% of women attain a coital climax. b. Many women (70–80%) require manual clitoral stimulation...|author1=Joseph A. Flaherty|author2=John Marcell Davis|author3=Philip G. Janicak}}</ref><ref name="Kenneth Mah">{{cite journal |vauthors=Mah K, Binik YM | title = The nature of human orgasm: a critical review of major trends | journal = [[Clinical Psychology Review]] | volume = 21 | issue = 6 | pages = 823–856 |date=January 7, 2001 | pmid = 11497209 | doi = 10.1016/S0272-7358(00)00069-6 | quote = Women rated clitoral stimulation as at least somewhat more important than vaginal stimulation in achieving orgasm; only about 20% indicated that they did not require additional clitoral stimulation during intercourse.}}</ref><ref name="Kammerer-Doak">{{cite journal |vauthors=Kammerer-Doak D, Rogers RG | title = Female Sexual Function and Dysfunction | journal = Obstetrics and Gynecology Clinics of North America | volume = 35 | issue = 2 | pages = 169–183 |date=June 2008 | pmid = 18486835 | doi = 10.1016/j.ogc.2008.03.006 | quote = Most women report the inability to achieve orgasm with vaginal intercourse and require direct clitoral stimulation ... About 20% have coital climaxes...}}</ref> though indirect clitoral stimulation (for example, via vaginal intercourse) may also be sufficient (see [[Vaginal orgasm|orgasm in females]]).<ref name="Lloyd">{{cite book |first=Elisabeth Anne|last=Lloyd|title=The case of the female orgasm: bias in the science of evolution|isbn = 978-0-674-01706-1|publisher=Harvard University Press|year=2005|page=53|access-date=January 5, 2012 |url=https://books.google.com/books?id=6GFNvA6TvlwC&pg=PA53|oclc=432675780}}</ref><ref name="O'Connell">{{cite journal |vauthors=O'Connell HE, Sanjeevan KV, Hutson JM | s2cid = 26109805 | title = Anatomy of the clitoris | journal = The Journal of Urology | volume = 174 | issue = 4 Pt 1 | pages = 1189–95 | date = October 2005 | pmid = 16145367 | doi = 10.1097/01.ju.0000173639.38898.cd }}<br />{{cite web |last=Mascall |first=Sharon |title=Time for rethink on the clitoris | url = http://news.bbc.co.uk/2/hi/health/5013866.stm | date =June 11, 2006 | work = [[BBC News]] }}</ref> Because of this, some couples may engage in the [[woman on top position]] or the [[coital alignment technique]], a technique combining the "riding high" variation of the missionary position with pressure-counterpressure movements performed by each partner in rhythm with sexual penetration, to maximize clitoral stimulation.<ref name="Roberts"/><ref name="Hurlbert">{{cite journal |vauthors=Hurlbert DF, Apt C | title = The coital alignment technique and directed masturbation: a comparative study on female orgasm | journal = [[Journal of Sex & Marital Therapy]] | volume = 21 | issue = 1 | pages = 21–29 | year = 1995 | pmid = 7608994 | doi = 10.1080/00926239508405968 }}</ref>
[[File:Édouard-Henri Avril (24).jpg|thumb|right|[[Édouard-Henri Avril]] depiction of [[cunnilingus]] in the life of [[Sappho]]]]
Anal sex involves stimulation of the [[Human anus|anus]], anal cavity, sphincter valve or [[rectum]]; it most commonly means the insertion of a man's penis into another person's rectum, but may also mean the use of sex toys or fingers to penetrate the anus, or oral sex on the anus ([[anilingus]]), or [[Pegging (sexual practice)|pegging]].<ref name="Answer">{{cite book|author1-link=Barry Komisaruk|author1=Barry R. Komisaruk|author2=Beverly Whipple|author2-link=Beverly Whipple|author3=Sara Nasserzadeh|author3-link=Sara Nasserzadeh|author4 =Carlos Beyer-Flores|title=The Orgasm Answer Guide|isbn = 978-0-8018-9396-4|publisher=[[JHU Press]]|year=2009|pages=[https://archive.org/details/orgasmanswerguid00komi/page/108 108]–109|access-date=November 6, 2011|url=https://archive.org/details/orgasmanswerguid00komi|url-access =registration}}</ref>

Oral sex consists of all the sexual activities that involve the use of the mouth and throat to stimulate [[genitalia]] or anus. It is sometimes performed to the exclusion of all other forms of sexual activity, and may include the ingestion or absorption of semen (during [[fellatio]]) or vaginal fluids (during [[cunnilingus]]).<ref name="Weiten, 2008"/><ref name="Kamen">{{Cite book| author = Paula Kamen| title = Her Way: Young Women Remake the Sexual Revolution | isbn = 978-0-8147-4733-9| publisher = [[New York University Press]]| year = 2000|pages = 74–77| access-date=September 5, 2012|url=https://books.google.com/books?id=9bXq3Qc4py0C&pg=PA74}}</ref>

Fingering involves the digital manipulation of the clitoris, rest of the [[vulva]], vagina or anus for the purpose of sexual arousal and sexual stimulation; it may constitute the entire sexual encounter or it may be part of mutual masturbation, foreplay or other sexual activities.<ref name="Kinetics"/><ref name="Hite">{{cite book|last=Hite|first=Shere|author-link=Shere Hite|title=The Hite Report: A Nationwide Study of Female Sexuality |publisher=[[Seven Stories Press]]|year=2003|location=New York, NY|pages=512 pages|isbn=978-1-58322-569-1|access-date=March 2, 2012|url=https://books.google.com/books?id=s3OZaVn2wfkC&pg=PP1}}</ref><ref name="Carroll2">{{cite book | title =Sexuality Now: Embracing Diversity | publisher = [[Cengage Learning]] | year = 2009 | pages = 118, 252, and 264 | access-date =June 23, 2012 | url = https://books.google.com/books?id=5f8mQx7ULs4C&pg=PA118|isbn =978-0-495-60274-3| first = Janell L. | last = Carroll}}
</ref>

===Reproduction===
{{Main|Sexual reproduction|Human reproduction}}
[[File:Pregnancy chance by day near ovulation.jpg|thumb|Chance of [[human fertilization|fertilization]] by [[menstrual cycle]] day relative to ovulation<ref name="DunsonBaird1999">{{cite journal|last1=Dunson|first1=D.B.|author1-link=David Dunson|last2=Baird|first2=D.D.|author2-link=Donna Baird|last3=Wilcox|first3=A.J.|last4=Weinberg|first4=C.R.|author4-link=Clarice Weinberg|title=Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation|journal=Human Reproduction|volume=14|issue=7|year=1999|pages=1835–1839|issn=1460-2350|doi=10.1093/humrep/14.7.1835|pmid=10402400|doi-access=free}}</ref>]]
[[File:Coition of a Hemisected Man and Woman.jpg|thumb|upright=0.8|right|"Coition of a Hemisected Man and Woman" (c. 1492), an interpretation of what happens inside the body during coitus, by [[Leonardo da Vinci]]]]
Natural human reproduction involves penile–vaginal penetration,<ref name="Evan Jones">{{cite book |title=Human Reproductive Biology |isbn =978-0-12-088465-0 |publisher=[[Academic Press]] |year=2006 |pages=[https://archive.org/details/humanreproductiv0000jone_l0u3/page/205 205-206] |access-date=June 5, 2022 <!-- Coitus (sexual intercourse) --> |url=https://archive.org/details/humanreproductiv0000jone_l0u3|url-access=registration|author1=Richard Evan Jones |author2=Kristin H. López }}</ref> during which [[semen]], containing male gametes known as [[Spermatozoon|sperm]] cells or spermatozoa, is [[ejaculated]] through the penis into the vagina. The sperm passes through the [[vaginal vault]], [[cervix]] and into the [[uterus]], and then into the [[fallopian tube]]s. Millions of sperm are ejaculated to increase the chances of [[Human fertilization|fertilization]] (see [[Human sperm competition|sperm competition]]), but only one is sufficient to fertilize an egg or [[ovum]]. When a fertile ovum from the female is present in the fallopian tubes, the male gamete fertilizes the ovum, forming a new [[embryo]]. [[Pregnancy]] begins after the fertilized ovum is implanted in the lining of the uterus (the [[endometrium]]).<ref name="Evan Jones"/><ref name="Starr3">{{cite book| author = Cecie Starr|author2= Beverly McMillan|title = Human Biology| publisher = [[Cengage Learning]] | year = 2015 | page = 339| access-date = December 27, 2017 |isbn = 978-1-305-44594-9| url =https://books.google.com/books?id=lS5-BAAAQBAJ&pg=PT339}}</ref>

[[Pregnancy rate#Pregnancy rate for sexual intercourse|Pregnancy rates for sexual intercourse]] are highest during the [[menstrual cycle]] time from some five days before until approximately one day after ovulation (this is sometimes called the [[fertile window]]).<ref name=":1">{{Cite journal |last1=Gibbons |first1=Tatjana |last2=Reavey |first2=Jane |last3=Georgiou |first3=Ektoras X |last4=Becker |first4=Christian M |date=September 15, 2023 |editor-last=Cochrane Gynaecology and Fertility Group |title=Timed intercourse for couples trying to conceive |journal=Cochrane Database of Systematic Reviews |language=en |volume=2023 |issue=9 |pages=CD011345 |doi=10.1002/14651858.CD011345.pub3|pmid=37709293 |pmc=10501857 }}</ref> For optimal pregnancy chance, there are recommendations of [[vaginal intercourse]] every one or two days,<ref>{{cite web|url=https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/how-to-get-pregnant/art-20047611|title=How to get pregnant|website=[[Mayo Clinic]]|date=November 2, 2016|access-date=February 16, 2018}}</ref> or every two or three days.<ref>{{cite web|url=https://www.nice.org.uk/guidance/cg156/ifp/chapter/trying-for-a-baby|title=Fertility problems: assessment and treatment, Clinical guideline [CG156]|website=[[National Institute for Health and Care Excellence]]|date=February 20, 2013 |access-date=February 16, 2018}} Published date: February 2013. Last updated: September 2017</ref> Some people who are trying to conceive may choose to time vaginal intercourse with the fertile window, a practice that is sometimes called 'timed intercourse'.<ref name=":1" /> Timed intercourse using urine tests that predict ovulation may help improve the rate of pregnancy and live births for some couples trying to conceive such as those who have been trying for less than 12 months and who are under 40 years old; however, it is not clear from medical evidence if timed intercourse improves the rate of ultrasound-confirmed pregnancies and it is also not clear if timed intercourse has an effect on a person's level of stress or their quality of life.<ref name=":1" /> Studies have shown no significant difference between different [[sex positions]] and pregnancy rate, as long as it results in [[ejaculation]] into the vagina.<ref name=americanpregnancy>{{cite web|url=http://americanpregnancy.org/getting-pregnant-ebook/p7M7O0q1c71703C/gettingpregnant.pdf|title=The Essential Guide to Getting Pregnant|website=American Pregnancy Association|author=Philip B. Imler & David Wilbanks|date=November 2019|access-date=February 16, 2018|archive-date=June 1, 2018|archive-url=https://web.archive.org/web/20180601033115/http://americanpregnancy.org/getting-pregnant-ebook/p7M7O0q1c71703C/gettingpregnant.pdf|url-status=dead}}</ref>

When a [[sperm donor]] has sexual intercourse with a woman who is not his partner and for the sole purpose of impregnating the woman, this may be known as natural [[insemination]], as opposed to [[artificial insemination]]. Artificial insemination is a form of [[assisted reproductive technology]], which are methods used to achieve pregnancy by artificial or partially artificial means.<ref name="Bobick and Balaban">{{cite book|author1=James Bobick |author2=Naomi Balaban |title=The Handy Anatomy Answer Book|isbn=978-1-57859-328-6|publisher=[[Visible Ink Press]]|year=2008|pages=306–307|access-date=August 21, 2013|url=https://books.google.com/books?id=LBI2Sg2yYMoC&pg=PA305}}</ref> For artificial insemination, [[sperm donors]] may donate their sperm through a [[sperm bank]], and the insemination is performed with the express intention of attempting to impregnate the female; to this extent, its purpose is the medical equivalent of sexual intercourse.<ref name="Sharma">{{cite book|author=R.K. Sharma|title=Concise Textbook Of Forensic Medicine & Toxicology|isbn=978-81-312-1145-8|publisher=[[Elsevier|Elsevier India]]|year=2007|pages=113–116|access-date=October 13, 2013|url=https://books.google.com/books?id=_zAwlKX_zNwC&pg=PA113}}</ref><ref name="O'Toole">{{cite book|author=Mosby, Marie T. O'Toole|title=Mosby's Medical Dictionary|isbn=978-0-323-11258-1|publisher=[[Elsevier Health Sciences]]|year=2013|page=138|access-date=October 13, 2013|url=https://books.google.com/books?id=aW0zkZl0JgQC&pg=PA138}}</ref> [[Intracervical insemination|Intracervical insemination (ICI)]], which involves the deposit of (usually) raw semen in the vagina of a woman, is in effect a substitute for intercourse and is often contrasted with 'normal intercourse' in this context. Reproductive methods also extend to gay and lesbian couples. For gay male pairings, there is the option of [[Surrogacy|surrogate]] pregnancy; for lesbian couples, there is donor insemination in addition to choosing surrogate pregnancy.<ref name="Berkowitz">{{cite journal |vauthors=Berkowitz D, Marsiglio W | s2cid = 38458107 | year = 2007 | title = Gay Men: Negotiating Procreative, Father, and Family Identities | journal = Journal of Marriage and Family | volume = 69 | issue = 2| pages = 366–381 | doi = 10.1111/j.1741-3737.2007.00371.x }}</ref><ref name="Burda">{{Cite book| author = Joan M. Burda| title = Gay, lesbian, and transgender clients: a lawyer's guide | publisher = [[American Bar Association]]| year = 2008 |pages =69–74| isbn = 978-1-59031-944-4|access-date=July 28, 2011|url=https://books.google.com/books?id=QdzB1f8Y8Q8C&pg=PA69}}</ref> Some women use artificial insemination to become [[single mothers by choice]].<ref>{{cite journal |last1=Fiese |first1=Barbara |title=Single Mothers by Choice: Mother–Child Relationships and Children's Psychological Adjustment |journal=J Fam Psychol |date=2016 |volume=30 |issue=4 |pages=409–418 |doi=10.1037/fam0000188 |pmid=26866836 |pmc=4886836 }}</ref>

===Safe sex and birth control===
{{See also|Comparison of birth control methods}}
There are a variety of [[safe sex]] methods that are practiced by heterosexual and same-sex couples, including non-penetrative sex acts,<ref name="Kumar"/><ref name="Durham">{{cite book|title=The Person With HIV/AIDS: Nursing Perspectives|edition=3rd|isbn = 978-81-223-0004-8|publisher=[[Springer Publishing Company]]|year=2000|page=103|access-date=January 29, 2012|url=https://books.google.com/books?id=WSCQ4L8kSXsC&pg=PA103|author1=Jerry D. Durham |author2=Felissa R. Lashley }}</ref> and heterosexual couples may use oral or anal sex (or both) as a means of birth control.<ref name="Crooks">{{cite book | title = Our Sexuality | publisher = [[Cengage Learning]] | year = 2010 | pages = 286–289 | access-date = August 30, 2012 |isbn = 978-0-495-81294-4| url = https://books.google.com/books?id=MpRnPtmdRVwC&pg=PA286|quote=Noncoital forms of sexual intimacy, which have been called outercourse, can be a viable form of birth control. Outercourse includes all avenues of sexual intimacy other than penile–vaginal intercourse, including kissing, touching, mutual masturbation, and oral and anal sex. |author1=Robert Crooks |author2=Karla Baur }}</ref><ref>{{cite journal |vauthors=Feldmann J, Middleman AB | title = Adolescent sexuality and sexual behavior | journal = Current Opinion in Obstetrics and Gynecology | volume = 14 | issue = 5 | pages = 489–493 | year = 2002 | pmid = 12401976 | doi=10.1097/00001703-200210000-00008| s2cid = 29206790 }}</ref> However, pregnancy can still occur with anal sex or other forms of sexual activity if the penis is near the vagina (such as during [[intercrural sex]] or other [[genital-genital rubbing]]) and its sperm is deposited near the vagina's entrance and travels along the vagina's lubricating fluids; the risk of pregnancy can also occur without the penis being near the vagina because sperm may be transported to the vaginal opening by the vagina coming in contact with fingers or other non-genital body parts that have come in contact with semen.<ref>{{cite book|last=Thomas|first=R. Murray|title=Sex and the American teenager seeing through the myths and confronting the issues|year=2009|publisher=[[Rowman & Littlefield Education]]|location=Lanham, Md.|isbn=978-1-60709-018-2|page=81|url=https://books.google.com/books?id=gM9EFgsJHyoC&pg=PA81|access-date=October 21, 2015}}</ref><ref>{{cite book|last=Edlin|first=Gordon|title=Health & Wellness.|year=2012|publisher=[[Jones & Bartlett Learning]]|isbn=978-1-4496-3647-0|page=213|url=https://books.google.com/books?id=csGk6j5rlN0C&pg=PA213|access-date=October 21, 2015}}</ref>

Safe sex is a relevant [[harm reduction]] philosophy<ref name="Mercer">{{cite journal | vauthors = Chin HB, Sipe TA, Elder R, Mercer SL, Chattopadhyay SK, Jacob V, Wethington HR, Kirby D, Elliston DB, Griffith M, Chuke SO, Briss SC, Ericksen I, Galbraith JS, Herbst JH, Johnson RL, Kraft JM, Noar SM, Romero LM, Santelli J | title = The Effectiveness of Group-Based Comprehensive Risk-Reduction and Abstinence Education Interventions to Prevent or Reduce the Risk of Adolescent Pregnancy, Human Immunodeficiency Virus, and Sexually Transmitted Infections | journal = American Journal of Preventive Medicine | volume = 42 | issue = 3 | pages = 272–294 | year = 2012 | pmid = 22341164 | doi = 10.1016/j.amepre.2011.11.006 | url = http://www.ajpmonline.org/article/S0749-3797(11)00906-8/abstract | access-date = July 23, 2013 | archive-date = January 2, 2020 | archive-url = https://web.archive.org/web/20200102180246/https://www.ajpmonline.org/article/S0749-3797(11)00906-8/abstract | url-status = dead }}</ref> and [[condom]]s are used as a form of safe sex and contraception. Condoms are widely recommended for the prevention of [[sexually transmitted infections]] (STIs).<ref name="Mercer"/> According to reports by the [[National Institutes of Health]] (NIH) and [[World Health Organization]] (WHO), correct and consistent use of latex condoms reduces the risk of [[HIV/AIDS]] transmission by approximately 85–99% relative to risk when unprotected.<ref>{{cite conference|author=National Institute of Allergy and Infectious Diseases |author-link=National Institute of Allergy and Infectious Diseases |author2=National Institutes of Health, Department of Health and Human Services |title=Workshop Summary: Scientific Evidence on Condom Effectiveness for Sexually Transmitted Disease (STD) Prevention |pages=13–15 |date=July 20, 2001 |location=Hyatt Dulles Airport, Herndon, Virginia |url=http://www3.niaid.nih.gov/about/organization/dmid/PDF/condomReport.pdf |archive-url=https://web.archive.org/web/20100307132024/http://www3.niaid.nih.gov/about/organization/dmid/PDF/condomReport.pdf |archive-date=March 7, 2010 |access-date=March 20, 2009 |url-status=dead}}</ref><ref name="WHO condoms">{{cite web|title=Effectiveness of male latex condoms in protecting against pregnancy and sexually transmitted infections|publisher=[[World Health Organization]]|year=2000|access-date=July 23, 2013|url=https://www.who.int/mediacentre/factsheets/fs243/en/index.html|archive-url=https://web.archive.org/web/20100509064325/http://www.who.int/mediacentre/factsheets/fs243/en/index.html |archive-date=May 9, 2010 }}</ref> Condoms are rarely used for oral sex and there is significantly less research on behaviors with regard to condom use for anal and oral sex.<ref name="Kumar 2">{{cite book|title=Sexually Transmitted Infections E book| author = Bhushan Kumar, Somesh Gupta| publisher = [[Elsevier Health Sciences]] | year = 2014 | page = 122 |isbn = 978-81-312-2978-1| url =https://books.google.com/books?id=kQ9tAwAAQBAJ}}</ref> The most effective way to avoid sexually transmitted infections is to [[Sexual abstinence|abstain]] from sexual intercourse, especially vaginal, anal, and oral sexual intercourse.<ref name="Mercer"/>

Decisions and options concerning birth control can be affected by cultural reasons, such as religion, [[gender role]]s or [[folklore]].<ref name="Hales2">{{cite book | title = An Invitation to Health: Choosing to Change| publisher = [[Cengage Learning]]| year = 2010 | pages = 301–302| access-date = March 30, 2013 |isbn = 978-0-538-73655-8| url = https://books.google.com/books?id=yPa0LZXizO4C&pg=PA301 | author = Dianne Hales}}</ref> In the predominantly [[Catholic]] countries Ireland, Italy, and the Philippines, [[fertility awareness]] and the [[Calendar-based contraceptive methods|rhythm method]] are emphasized while disapproval is expressed with regard to other contraceptive methods.<ref name="Hales"/> Worldwide, [[Sterilization (medicine)|sterilization]] is a more common birth control method,<ref name="Hales"/> and use of the [[intrauterine device]] (IUD) is the most common and effective way of reversible contraception.<ref name="Hales"/><ref name=Winner2012>{{cite journal |vauthors=Winner B, Peipert JF, Zhao Q, Buckel C, Madden T, Allsworth JE, Secura GM | title = Effectiveness of long-acting reversible contraception | journal = N. Engl. J. Med. | volume = 366 | issue = 21 | pages = 1998–2007 | year = 2012 | pmid = 22621627 | doi = 10.1056/NEJMoa1110855 | s2cid = 16812353 | url = https://digitalcommons.wustl.edu/cgi/viewcontent.cgi?article=3776&context=open_access_pubs | doi-access = free }}</ref> Conception and contraception are additionally a life-and-death situation in [[developing countries]], where one in three women give birth before age 20; however, 90% of [[unsafe abortion]]s in these countries could be prevented by effective contraception use.<ref name="Hales"/>

The [[National Survey of Sexual Health and Behavior]] (NSSHB) indicated in 2010 that "1 of 4 acts of vaginal intercourse are condom-protected in the U.S. (1 in 3 among singles)," that "condom use is higher among black and Hispanic Americans than among white Americans and those from other racial groups," and that "adults using a condom for intercourse were just as likely to rate the sexual extent positively in terms of arousal, pleasure and orgasm than when having intercourse without one".<ref name="NSSHB">{{cite journal |title=Findings from the National Survey of Sexual Health and Behavior, Centre for Sexual Health Promotion, Indiana University |journal= [[The Journal of Sexual Medicine]] |volume=7 |issue=Supplement 5 |page=4 |year=2010 |access-date=March 4, 2011|url=http://www.kinseyinstitute.org/resources/FAQ.html}}</ref>

===Prevalence===
Penile–vaginal penetration is the most common form of sexual intercourse.<ref name="Alters"/><ref name="Carroll"/> Studies indicate that most heterosexual couples engage in vaginal intercourse nearly every sexual encounter.<ref name="Carroll"/> The National Survey of Sexual Health and Behavior (NSSHB) reported in 2010 that vaginal intercourse is "the most prevalent sexual behavior among men and women of all ages and ethnicities".<ref name="Carroll"/> Clint E. Bruess et al. stated that it "is the most frequently studied behavior" and is "often the focus of sexuality education programming for youth."<ref name="Bruess">{{cite book| author = Clint E. Bruess| author2 = Elizabeth Schroeder|title = Sexuality Education Theory and Practice| publisher = [[Jones & Bartlett Publishers]] | year = 2013 | page = 152 | access-date = December 5, 2014 |isbn = 978-1-4496-4928-9| url =https://books.google.com/books?id=WWFW6-kkAVoC&pg=PA152}}</ref> Weiten et al. said that it "is the most widely endorsed and practiced sexual act in our society."<ref name="Weiten3"/>

Regarding oral or anal intercourse, the CDC stated in 2009, "Studies indicate that oral sex is commonly practiced by sexually active male-female and same-gender couples of various ages, including adolescents."<ref name="CDC, oral sex"/> Oral sex is significantly more common than anal sex.<ref name="Weiten3"/><ref name="Aggleton 1"/> The 2010 NSSHB study reported that vaginal intercourse was practiced more than insertive anal intercourse among men, but that 13% to 15% of men aged 25 to 49 practiced insertive anal intercourse. Receptive anal intercourse was infrequent among men, with approximately 7% of men aged 14 to 94 years old having said that they were a receptive partner during anal intercourse. The study said that fewer women reported engaging in anal sex than other partnered sexual behaviors. It was estimated that 10% to 14% of women aged 18 to 39 years old practiced anal sex in the past 90 days, and that most of the women who engage in anal sex said they practiced it once a month or a few times a year.<ref name="Carroll"/>

===={{anchor|sexarche}}Age at first intercourse====
The prevalence of sexual intercourse has been compared cross-culturally. In 2003, Michael Bozon of the French [[Institut national d'études démographiques]] conducted a cross-cultural study titled "At what age do women and men have their first sexual intercourse?" In the first group of the contemporary cultures he studied, which included [[sub-Saharan Africa]] (listing [[Mali]], [[Senegal]] and [[Ethiopia]]), the data indicated that the age of men at sexual initiation in these societies is at later ages than that of women, but is often extra-marital; the study considered the [[Indian subcontinent]] to also fall into this group, though data was only available from [[Nepal]].<ref name="Bozon">{{cite journal |last=Bozon |first=Michael |year=2003 |title=At what age do women and men have their first sexual intercourse? World comparisons and recent trends |journal=Population and Societies |volume=391 |pages=1–4 |url=https://www.ined.fr/fichier/s_rubrique/247/english_391.en.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160304091955/https://www.ined.fr/fichier/s_rubrique/247/english_391.en.pdf |archive-date=March 4, 2016}}</ref><ref name="Caselli">{{cite book| author = Graziella Caselli| author2 = Guillaume Wunsch| author3 = Daniel Courgeau| author4 = Jacques Vallin| title = Demography&nbsp;– Analysis and Synthesis: A Treatise in Population| publisher = [[Academic Press]] | year = 2005 | pages = 490–501 | access-date = September 6, 2013 |isbn = 978-0-12-765660-1| url=https://books.google.com/books?id=nmgNXoiAiU4C&pg=PA491}}</ref> In the second group, the data indicated families encouraged daughters to delay marriage, and to abstain from sexual activity before that time. However, sons are encouraged to gain experience with older women or prostitutes before marriage. Age of men at sexual initiation in these societies is at lower ages than that of women; this group includes [[southern Europe|south European]] and Latin cultures (Portugal, Greece and Romania are noted) and such from [[Latin America]] (Brazil, [[Chile]], and the [[Dominican Republic]]). The study considered many Asian societies to also fall into this group, although matching data was only available from [[Thailand]].<ref name="Bozon" /><ref name="Caselli" /> In the third group, age of men and women at sexual initiation was more closely matched; there were two sub-groups, however. In non-Latin, Catholic countries (Poland and [[Lithuania]] are mentioned), age at sexual initiation was higher, suggesting later marriage and reciprocal valuing of male and female virginity. The same pattern of late marriage and reciprocal valuing of virginity was reflected in [[Singapore]] and [[Sri Lanka]]. The study considered China and Vietnam to also fall into this group, though data were not available.<ref name="Bozon" /><ref name="Caselli" /> In northern and eastern European countries, age at sexual initiation was lower, with both men and women involved in sexual intercourse before any union formation; the study listed Switzerland, Germany and the Czech Republic as members of this group.<ref name="Bozon" /><ref name="Caselli" />

Concerning United States data, tabulations by the [[National Center for Health Statistics]] report that the age of first sexual intercourse was 17.1 years for both males and females in 2010.<ref name="CDC abc_list_s">{{cite web|title=Key Statistics from the National Survey of Family Growth|access-date=February 9, 2013|publisher=[[Centers for Disease Control and Prevention]] (CDC)|url=https://www.cdc.gov/nchs/nsfg/abc_list_s.htm}}</ref> The CDC stated that 45.5 percent of girls and 45.7 percent of boys had engaged in sexual activity by 19 in 2002; in 2011, reporting their research from 2006 to 2010, they stated that 43% of American unmarried teenage girls and 42% of American unmarried teenage boys have ever engaged in sexual intercourse.<ref name="CDC statistics">{{cite web|title=Teenagers in the United States: Sexual Activity, Contraceptive Use, and Childbearing, 2006–2010 National Survey of Family Growth|access-date=December 26, 2012|publisher=[[Centers for Disease Control and Prevention]] (CDC)|url=https://www.cdc.gov/nchs/data/series/sr_23/sr23_031.pdf}}</ref> The CDC also reports that American girls will most likely lose their virginity to a boy who is 1 to 3 years older than they are.<ref name="CDC statistics"/> Between 1988 and 2002, the percentage of people in the U.S. who had sexual intercourse between the ages of 15 and 19 fell from 60 to 46 percent for never-married males, and from 51 to 46 percent for never-married females.<ref name="CDC sr23_024">{{cite web|title=Teenagers in the United States: Sexual Activity, Contraceptive Use, and Childbearing, 2002|access-date=February 9, 2013|publisher=[[Centers for Disease Control and Prevention]] (CDC)|url=https://www.cdc.gov/nchs/data/series/sr_23/sr23_024.pdf}}</ref>