Promiscuity is the practice of having sex frequently with different partners or being indiscriminate in the choice of sexual partners.^[1] The term can carry a moral judgment if the social ideal for sexual activity is monogamous relationships. A common example of behavior viewed as promiscuous by many cultures is the one-night stand, and its frequency is used by researchers as a marker for promiscuity.^[2]

What sexual behavior is considered promiscuous varies between cultures, as does the prevalence of promiscuity.

Different standards are often applied to different genders and civil statutes.

Feminists have traditionally argued a significant double standard exists between how men and women are judged for promiscuity. Historically, stereotypes of the promiscuous woman have tended to be negative, such as "the slut" or "the harlot", while male stereotypes have been more varied, some expressing approval, such as "the stud" or "the player", while others imply societal deviance, such as "the womanizer" or "the philanderer". A scientific study published in 2005 found that promiscuous men and women are both prone to derogatory judgment.^[3]

Promiscuity is common in many animal species.^[4] Some species have promiscuous mating systems, ranging from polyandry and polygyny to mating systems with no stable relationships where mating between two individuals is a one-time event. Many species form stable pair bonds, but still mate with other individuals outside the pair. In biology, incidents of promiscuity in species that form pair bonds are usually called extra-pair copulations.

Accurately assessing people's sexual behavior is difficult, since strong social and personal motivations occur, depending on social sanctions and taboos, for either minimizing or exaggerating reported sexual activity.

American experiments in 1978 and 1982 found the great majority of men were willing to have sex with women they did not know, of average attractiveness, who propositioned them.

No woman, by contrast, agreed to such propositions from men of average attractiveness.

While men were in general comfortable with the requests, regardless of their willingness, women responded with shock and disgust.^[5]

The number of sexual partners people have had in their lifetimes varies widely within a population.

A 2007 nationwide survey in the United States found the median number of female sexual partners reported by men was seven and the median number of male partners reported by women was four.

The men possibly exaggerated their reported number of partners, women reported a number lower than the actual number, or a minority of women had a sufficiently larger number than most other women to create a mean significantly higher than the median, or all of the above.

About 29% of men and 9% of women reported to have had more than 15 sexual partners in their lifetimes.^[6] Studies of the spread of sexually transmitted diseases consistently demonstrate a small percentage of the studied population has more partners than the average man or woman, and a smaller number of people have fewer than the statistical average. An important question in the epidemiology of sexually transmitted infections is whether or not these groups copulate mostly at random with sexual partners from throughout a population or within their social groups.

A 2006 systematic review analyzing data from 59 countries worldwide found no association between regional sexual behavior tendencies, such as number of sexual partners, and sexual-health status. Much more predictive of sexual-health status are socioeconomic factors like poverty and mobility.^[7] Other studies have suggested that people with multiple casual sex partners are more likely to be diagnosed with sexually transmitted infections.^[8]

Severe and impulsive promiscuity, along with a compulsive urge to engage in illicit sex with attached individuals is a common symptom of borderline personality disorder, histrionic personality disorder, narcissistic personality disorder and antisocial personality disorder but most promiscuous individuals do not have these disorders.^[9]

In 2008, a U.S. university study of international promiscuity found that Finns have had the largest number of sex partners in the industrialized world, and British people have the largest number among big western industrial nations. The study measured one-night stands, attitudes to casual sex, and number of sexual partners.^[10][11][12] A 2014 nationwide survey in the United Kingdom named Liverpool the country's most promiscuous city.^[2]

Britain's position on the international index "may be linked to increasing social acceptance of promiscuity among women as well as men".

Britain's ranking was "ascribed to factors such as the decline of religious scruples about extramarital sex, the growth of equal pay and equal rights for women and a highly sexualised popular culture".^[10][11][12]

The top-10-ranking OECD nations with a population over 10 million on the study's promiscuity index, in descending order, were the United Kingdom, Germany, the Netherlands, the Czech Republic, Australia, the United States, France, Turkey, Mexico, and Canada.^[10][11][12]

A nonscientific survey conducted in 2007 by condom-maker Durex measured promiscuity by a total number of sexual partners. The survey found Austrian men had the highest number of sex partners of males globally with 29.3 sexual partners on average. New Zealand women had the highest number of sex partners for females in the world with an average of 20.4 sexual partners. In all of the countries surveyed, except New Zealand, men reported more sexual partners than women.^[14]

The data can differ quite drastically between studies due to the small number of people that participate.

A study funded by Durex, published in 2009 (collected in 2006) shows in all counties surveyed, except New Zealand, men reported fewer sexual partners than women.

In this case, New Zealand women were the only country to report a lower average number of partners than men.^[15]

One review found the people from developed Western countries had more sex partners than people from developing countries in general, while the rate of STIs was higher in developing countries.^[7]

According to the 2005 Global Sex Survey by Durex, people have had on average nine sexual partners, the most in Turkey (14.5) and Australia (13.3), and the least in India (3) and China (3.1).^[16]

In many cases, the population of each country that participates is approximately 1000 people and can equate to less than 0.0003% of the population, e.g. the 2017 survey of 42 nations surveyed only 33,000 people.

In India, data was collected from less than 0.000001% of the total population at that time.^[17][15][18]

A 1994 study in the United States, which looked at the number of sexual partners in a lifetime, found 20% of heterosexual men had one partner, 55% had two to 20 partners, and 25% had more than 20 partners.^[19] More recent studies have reported similar numbers.^[20]

A 1989 study found having over 100 partners to be present though rare among homosexual males.^[21] General Social Survey data indicates that the distribution of partner numbers among men who have sex exclusively with men and men who have sex exclusively with women is similar, but that differences appear in the proportion of those with very high number of partners, which is larger among gay men, but that in any case makes up a small minority for both groups.^[22] OkCupid discovered a similar pattern in the data collected from its vast number of users, published in 2010: the median number of self-reported lifetime sexual partners for both gay and straight men was six; however, a small minority of gay men (2%) were having a disproportionate share of all self-reported gay sex (23%).^[23] According to updated OkCupid data published in 2014, gay male users self-reported a lower median of lifetime sex partners than straight male users: four for gay men and five for straight men.^[24] A 2007 study reported that two large population surveys found "the majority of gay men had similar numbers of unprotected sexual partners annually as straight men and women."^[25][26]

The words 'womanizer', 'playboy', 'stud', 'player', 'ladies' man', 'lady killer', and 'rake' may be used in reference to a man who has romantic affairs or sexual relations, or both, with women, and who will not be monogamous. The names of real and fictional seducers have become eponymous for such promiscuous men. The most famous include Lord Byron, John F. Kennedy, Errol Flynn, Warren Beatty, Hugh Hefner, Wilt Chamberlain, Gene Simmons, Howard Hughes, and the historical Giacomo Casanova (1725–98).^[27] Others include Elvis Presley, Frank Sinatra, Dean Martin, and Steve McQueen.

Famous historical fictional seducers include Don Juan, who first appeared in the 17th century, the fictional Vicomte de Valmont from Choderlos de Laclos's 18th-century novel Les Liaisons Dangereuses (Dangerous Liaisons), and Lothario from Nicholas Rowe's 1703 play The Fair Penitent

More recent fictional characters who can be considered womanizers include Tony Soprano, James Bond, Chuck Bass, James T. Kirk, Tony Stark, Glenn Quagmire, Joe Quimby, Bruce Wayne, Charlie Harper, Sam Malone, Joey Tribbiani, Popeye Doyle, Donald Draper, Hank Moody, Arthur "Fonzie" Fonzarelli, Barney Stinson, Tim Riggins and Drake Parker.

During the English Restoration period (1660–88), the term 'rake' was used glamorously: the Restoration rake is a carefree, witty, sexually irresistible aristocrat typified by Charles II's courtiers, the Earl of Rochester and the Earl of Dorset, who combined riotous living with intellectual pursuits and patronage of the arts. The Restoration rake is celebrated in the Restoration comedy of the 1660s and the 1670s. After the reign of Charles II, and especially after the Glorious Revolution of 1688, the rake was perceived negatively and became the butt of moralistic tales in which his typical fate was debtor's prison, permanent venereal disease, and, in the case of William Hogarth's A Rake's Progress, syphilis-induced insanity and internment in Bedlam.

In 1994, a study in the United States found almost all married heterosexual women reported having sexual contact only with their husbands, and unmarried women almost always reported having no more than one sexual partner in the past three months.

Lesbians who had a long-term partner reported having fewer outside partners than heterosexual women.^[21] More recent research, however, contradicts the assertion that heterosexual women are largely monogamous.

A 2002 study estimated that 45% to 55% of married heterosexual women engage in sexual relationships outside of their marriage.^[28] While the estimates for heterosexual males in the same study were greater (50–60%), the data indicate a significant portion of married heterosexual women have or have had sexual partners other than their spouse, as well.^[28]

One possible explanation for hyper sexuality is child sexual abuse (CSA) trauma.

Many studies have examined the correlation between CSA and risky sexual behavior.

Rodriguez-Srednicki and Ofelia examined the correlation of CSA experienced by women and their self-destructive behavior as adults using a questionnaire.

The diversity and ages of the women varied.

Slightly fewer than half the women reported CSA while the remainder reported no childhood trauma.

The results of the study determined that self-destructive behaviors, including hypersexuality, correlates with CSA in women.^[29] CSA can create sexual schemas that result in risky sexual behavior.^[30] This can play out in their sexual interactions as girls get older. The sexual behaviors of women that experienced CSA differed from those of women without exposure to CSA. Studies show CSA survivors tend to have more sexual partners and engage in higher risk sexual behaviors.^[31]

Since at least 1450, the word 'slut' has been used, often pejoratively, to describe a sexually promiscuous woman.^[32] In and before the Elizabethan and Jacobean eras, terms like "strumpet" and "whore" were used to describe women deemed promiscuous, as seen, for example, in John Webster's 1612 play The White Devil

Thornhill and Gangestad found that women are much more likely to sexually fantasize about and be attracted to extra-pair men during the fertile phase of the menstrual cycle than the luteal phase, whereas attraction to the primary partner does not change depending on the menstrual cycle.^[33]*Th]]*Th]]Th]] 2004 study by Pillsworth, Hasselton and Buss contradicted this, finding greater in-pair sexual attraction during this phase and no increase in attraction to extra-pair men.

Evolutionary psychologists propose that a conditional human tendency for promiscuity is inherited from hunter-gatherer ancestors. Promiscuity increases the likelihood of having children, thus "evolutionary" fitness. According to them, female promiscuity is advantageous in that it allows females to choose fathers for their children who have better genes than their mates, to ensure better care for their offspring, have more children, and as a form of fertility insurance.^[35] Male promiscuity was likely advantageous because it allowed males to father more children.

Primitive promiscuity or original promiscuity was the 19th-century hypothesis that humans originally lived in a state of promiscuity or "hetaerism" prior to the advent of society as we understand it.^{[36][37][38][39][40]}

Many animal species, such as bonobos^[41] and chimpanzees, are promiscuous as a rule; they do not form pair bonds. Although social monogamy occurs in about 90% of avian species and about 3% of mammalian species, an estimated 90% of socially monogamous species exhibit individual promiscuity in the form of copulation outside the pair bond.^[4][42][43]

In the animal world, some species, including birds such as swans and fish such as Neolamprologus pulcher, once believed monogamous, are now known to engage in extra-pair copulations. One example of extra-pair fertilization (EPF) in birds is the black-throated blue warblers. Though it is a socially monogamous species, both males and females engage in EPF.^[44]

The Darwin-Bateman paradigm, which states that males are typically eager to copulate while females are more choosy about whom to mate with, has been confirmed by a meta-analysis.^[45]