Human sexual activity

Human sexual activity, or human sexual practice or human sexual behavior, is the manner in which humans experience and express their sexuality. People engage in a variety of sexual acts from time to time, and for a wide variety of reasons. Sexual activity normally results in sexual arousal and physiological changes in the aroused person, some of which are pronounced while others are more subtle. Sexual activity also includes conduct and activities which are intended to arouse the sexual interest of another, such as strategies to find or attract partners (mating and display behavior), and personal interactions between individuals, such as flirting and foreplay.

Human sexual activity has sociological, cognitive, emotional, behavioral and biological aspects, including physiological processes such as the reproductive mechanism, the sex drive and pathology; sexual intercourse and sexual behavior in all its forms; and personal bonding and shared emotions during sexual activity.

In some cultures, sexual activity is considered acceptable only within marriage, although premarital and extramarital sex are also common. Some sexual activities are illegal either universally or in some countries, and some are considered against the norms of a society. For example, sexual activity with a person below some age of consent and sexual assault in general are criminal offenses in most jurisdictions.

Types
Sexual activity can be classified in a number of ways. It can be divided into acts which involve one person, such as masturbation, or two or more people such as vaginal sex, anal sex, oral sex, or mutual masturbation. If there are more than two participants in the sex act, it may be referred to as group sex. Autoerotic sexual activity can involve use of dildos, vibrators, anal beads, and other sex toys, though these devices can also be used with a partner.

Sexual activity can be classified into the gender and sexual orientation of the participants, as well as by the relationship of the participants. For example, the relationships can be ones of marriage, intimate partners, casual sex partners or anonymous. Sexual activity can be regarded as conventional or as alternative, involving, for example, fetishism, urolagnia, and/or BDSM activities. Fetishism can take many forms ranging from the desire for certain body parts, for example large breasts, armpits or foot worship. The object of desire can often be shoes, boots, lingerie, clothing, leather or rubber items.

Sexual activity can also be consensual or under force or duress, or lawful/illegal or otherwise contrary to social norms or generally accepted sexual morals. Some non-conventional autoerotic practices can be dangerous. These include erotic asphyxiation and self-bondage. The potential for injury or even death that exists while engaging in the partnered versions of these fetishes (choking and bondage, respectively) becomes drastically increased in the autoerotic case due to the isolation and lack of assistance in the event of a problem.

Stages of physiological arousal during sexual activity
The physiological responses during sexual activity are fairly similar for both men and women and there are four phases.
 * During the excitement phase, muscle tension and blood flow increase in and around the sexual organs, heart and respiration increase and blood pressure rises. Men and women experience a "sex flush" on the skin of the upper body and face. Typically, a woman's vagina becomes lubricated and her clitoris becomes swollen.
 * During the plateau phase, heart rate and muscle tension increase further. A man's urinary bladder closes to prevent urine from mixing with semen. A woman's clitoris may withdraw slightly and there is more lubrication, outer swelling and muscles tighten and reduction of diameter.
 * During the orgasm phase, breathing becomes extremely rapid and the pelvic muscles begin a series of rhythmic contractions. Both men and women experience quick cycles of muscle contraction of lower pelvic muscles and women often experience uterine and vaginal contractions; this experience can be described as intensely pleasurable, but roughly 15% of women never experience orgasm and half report having faked it. A large genetic component is associated with how often women experience orgasm.
 * During the resolution phase, muscles relax, blood pressure drops, and the body returns to its resting state. Though generally reported that women do not experience a refractory period and thus can experience an additional orgasm, or multiple orgasms, soon after the first, some sources state that both men and women experience a refractory period because women may also experience a period after orgasm in which further sexual stimulation does not produce excitement. This period may last from minutes to days and is typically longer for men than women.

Reasons for sexual activity
People engage in sexual activity for any of a multitude of possible reasons. Although the primary evolutionary purpose of sexual activity is reproduction, research on the college students suggested that people have sex for four general reasons: physical attraction, as a means to an end, to increase emotional connection, and to alleviate insecurity.

Most people engage in sexual activity because of the sexual pleasure they derive from the activity, in which the most heightened pleasure is derived through orgasm. Erotic pleasure can also be experienced during foreplay and from flirting, and from fetish or BDSM activities.

Most commonly, people engage in sexual activity with a person to whom they are sexually attracted; but at times, a person may engage in a sexual activity solely for the sexual pleasure of the partner, such as because of an obligation they may have to the partner or because of love, sympathy or pity they may feel for the partner.

Also, a person may engage in sexual activity for purely monetary considerations, or to obtain some advantage from either the partner or the activity. A man and woman may engage in sexual intercourse with the objective of conception. Some people engage in hate sex, which occurs between two people who strongly dislike or annoy each other. It is related to the idea that opposition between two people can heighten sexual tension, attraction and interest.

It has been shown that sexual activity plays a large part in the interaction of social species. Joan Roughgarden, in her book Diversity, Gender, and Sexuality in Nature and People, postulates that this applies equally to humans as it does to other social species. She explores the purpose of sexual activity and demonstrates that there are many functions facilitated by such activity including pair bonding, group bonding, dispute resolution and reproduction.

Frequency
The frequency of sexual activity might range from zero (sexual abstinence) to 15 or 20 times a week. In the United States, the average frequency of sexual intercourse for married couples is 2 to 3 times a week. It is generally recognized that postmenopausal women experience declines in frequency of sexual intercourse and that average frequency of intercourse declines with age. According to the Kinsey Institute, the average frequency of sexual intercourse in the US is 112 times per year (age 18–29), 86 times per year (age 30–39), and 69 times per year (age 40–49).

General health and sexually transmitted infections
Sexual activity is a normal physiological function, as it contributes to physical health just like walking, but it comes with risks. There are four main risks that arise from sexual activity. These are unwanted pregnancy, contracting a sexually transmitted infection, physical injury, and psychological injuries.

Sexual activity that involves sexual intercourse or even contact of semen with the vagina or vulva carries the chance of pregnancy. People who want to engage in such behaviors with a reduced chance of pregnancy employ any of a variety of available contraception methods, such as birth control pills, the use of a condom, diaphragms, spermicides, hormonal contraception, and sterilization.

Sexual activity that involves contact with another person's bodily fluids carries the risk of contracting a sexually transmitted infection such as HIV/AIDS, hepatitis B, chlamydia, syphilis, gonorrhea, genital herpes, trichomoniasis or HPV. HIV/AIDS is a major public health issue in much of Sub-Saharan Africa, especially Southern Africa. Safer sex practices reduce these risks. These precautions are often seen as less necessary for sex partners in committed relationships, if they are known to be free of disease. Some people require potential sex partners to be tested for sexually transmitted diseases before engaging in sex.

Other risks
Physical risks vary with the type of sexual activity being engaged in. The medical condition and physical limitations of the participants must be kept in mind. The risk factors are increased by a condition (temporary or permanent) which impairs a person's judgment, such as excess alcohol or other drugs, or emotional states such as loneliness, depression or euphoria. Age and mental capacity of the participants can also affect the risks of sexual activity.

Sexual dysfunction is the inability to react emotionally or physically to sexual stimulation in a way projected of the average healthy person; it can affect different stage in the sexual response cycles, which are desire, excitement and orgasm. In the media, sexual dysfunction is often associated with men, but in actuality, it is more commonly observed in females (43 percent) than males (31 percent).

Aging
Typically, older men and women maintaining interest in sexual interest and activity could be therapeutic; it is a source of expressing their love and care for one another. Aging women with an intimate partner have been found to be in a better state of mental health compared to women lacking intimacy in their relationships. Factors such as biological and psychological factors, diseases, mental conditions, boredom with the relationship, and widowhood have been found to contribute with the common decrease in sexual interest and activity in old age. National sex surveys given in Finland in the 1990s revealed aging men, as a result a female widowhood, had a higher incidence of sexual intercourse compared to aging women and that women were more likely to report a lack of sexual desire compared to men. Regression analysis, factors considered important to female sexual activity included: sexual desire, valuing sexuality, and a healthy partner, while high sexual self-esteem, good health, and active sexual history were important to male sexual activity. Both aging genders agreed they needed good health, good sexual functioning, positive sexual self-esteem, and a sexually skilful partner to maintain sexual desire.

Heterosexuality
Heterosexuality is the romantic or sexual attraction to the opposite sex. Heterosexual sexual practices are subject to laws in many places. In some countries, mostly those where religion has a strong influence on social policy, marriage laws serve the purpose of encouraging people to have sex only within marriage. Sodomy laws were seen as discouraging same-sex sexual practices, but may affect opposite-sex sexual practices. Laws also ban adults from committing sexual abuse, committing sexual acts with anyone under an age of consent, performing sexual activities in public, and engaging in sexual activities for money (prostitution). Though these laws cover both same-sex and opposite-sex sexual activities, they may differ in regard to punishment, and may be more frequently (or exclusively) enforced on those who engage in same-sex sexual activities.

Different-sex sexual practices may be monogamous, serially monogamous, or polyamorous, and, depending on the definition of sexual practice, abstinent or autoerotic (including masturbation). Additionally, different religious and political movements have tried to influence or control changes in sexual practices including courting and marriage, though in most countries changes occur at a slow rate.

Homosexuality
Homosexuality is the romantic or sexual attraction to the same sex. People with a homosexual orientation can express their sexuality in a variety of ways, and may or may not express it in their behaviors. Research indicates that many gay men and lesbians want, and succeed in having, committed and durable relationships. For example, survey data indicate that between 40% and 60% of gay men and between 45% and 80% of lesbians are currently involved in a romantic relationship.

It is possible for a person whose sexual identity is mainly heterosexual to engage in sexual acts with people of the same sex. For example, mutual masturbation in the context of what may be considered normal heterosexual teen development. Gay and lesbian people who pretend to be heterosexual are often referred to as being closeted (hiding their sexuality in "the closet"). "Closet case" is a derogatory term used to refer to people who hide their sexuality. Making that orientation public can be called "coming out of the closet" in the case of voluntary disclosure or "outing" in the case of disclosure by others against the subject's wishes. Among some communities (called "men on the DL" or "down-low"), same-sex sexual behavior is sometimes viewed as solely for physical pleasure. Men who have sex with men, as well as women who have sex with women, or men on the "down-low" may engage in sex acts with members of the same sex while continuing sexual and romantic relationships with the opposite sex.

People who engage exclusively in same-sex sexual practices may not identify themselves as gay or lesbian. In sex-segregated environments, individuals may seek relationships with others of their own gender (known as situational homosexuality). In other cases, some people may experiment or explore their sexuality with same (and/or different) sex sexual activity before defining their sexual identity. Despite stereotypes and common misconceptions, there are no forms of sexual acts exclusive to same-sex sexual behavior that cannot also be found in opposite-sex sexual behavior, except those involving the meeting of the genitalia between same-sex partners – tribadism (generally vulva-to-vulva rubbing, commonly known by its "scissoring" position) and frot (generally penis-to-penis rubbing).

Bisexuality and pansexuality
People who have a romantic or sexual attraction to both sexes are referred to as bisexual, although the American Institute of Bisexuality defines it as physical or romantic attraction to "those of the same gender or to those of another gender". People who have a distinct but not exclusive preference for one sex/gender over the other may also identify themselves as bisexual. Like gay and lesbian individuals, bisexual people who pretend to be heterosexual are often referred to as being closeted.

Pansexuality (also referred to as omnisexuality) may or may not be subsumed under bisexuality, with some sources stating that bisexuality encompasses sexual or romantic attraction to all gender identities. Pansexuality is characterized by the potential for aesthetic attraction, romantic love, or sexual desire towards people without regard for their gender identity or biological sex. Some pansexuals suggest that they are gender-blind; that gender and sex are insignificant or irrelevant in determining whether they will be sexually attracted to others. As defined in the Oxford English Dictionary, pansexuality "encompasses all kinds of sexuality; not limited or inhibited in sexual choice with regards to gender or practice".

General attitudes
Most people experiment with a range of sexual activities during their lives, although they tend to engage in only a few of these regularly. Some people enjoy many different sexual activities, while others avoid sexual activities altogether for religious or other reasons (see chastity, sexual abstinence, asexuality). Some prefer monogamous relationships for sex, and others may prefer many different partners throughout their lives.

Alex Comfort and others propose three potential social aspects of intercourse in humans, which are not mutually exclusive: reproductive, relational, and recreational. The development of the contraceptive pill and other highly effective forms of contraception in the mid- and late 20th century has increased people's ability to segregate these three functions, which still overlap a great deal and in complex patterns. For example: A fertile couple may have intercourse while using contraception to experience sexual pleasure (recreational) and also as a means of emotional intimacy (relational), thus deepening their bonding, making their relationship more stable and more capable of sustaining children in the future (deferred reproductive). This same couple may emphasize different aspects of intercourse on different occasions, being playful during one episode of intercourse (recreational), experiencing deep emotional connection on another occasion (relational), and later, after discontinuing contraception, seeking to achieve pregnancy (reproductive, or more likely reproductive and relational).

Adolescents
A 1999 survey of students indicated that approximately 40% of ninth graders nationwide report having sexual intercourse. This figure rises with each grade. Males are more sexually active than females at each of the grade levels surveyed. Sexual activity of young adolescents differs in ethnicity as well. A higher percent of African American and Hispanic adolescents are sexually active than White adolescents.

Religious and ethical
Most world religions have sought to address the moral issues that arise from people's sexuality in society and in human interactions. Each major religion has developed moral codes covering issues of sexuality, morality, ethics etc. Though these moral codes do not address issues of sexuality directly, they seek to regulate the situations which can give rise to sexual interest and to influence people's sexual activities and practices. However, the impact of religious teaching has at times been limited. For example, though most religions disapprove of extramarital sexual relations, it has always been widely practiced. Nevertheless, these religious codes have always had a strong influence on peoples' attitudes to issues of modesty in dress, behavior, speech etc.

On the other hand, some people adopt the view that pleasure is its own justification for sexual activity. Hedonism is a school of thought which argues that pleasure is the only intrinsic good.

Human sexual activity, like many other kinds of activity engaged in by humans, is generally influenced by social rules that are culturally specific and vary widely. These social rules are referred to as sexual morality (what can and can not be done by society's rules) and sexual norms (what is and is not expected).

Sexual ethics, morals, and norms relate to issues including deception/honesty, legality, fidelity and consent. Some activities, known as sex crimes in some locations, are illegal in some jurisdictions, including those conducted between (or among) consenting and competent adults (examples include sodomy law and adult-adult incest).

Some people who are in a relationship but want to hide polygamous activity (possibly of opposite sexual orientation) from their partner, may solicit consensual sexual activity with others through personal contacts, online chat rooms, or, advertising in select media.

Swinging, on the other hand, involves singles or partners in a committed relationship engaging in sexual activities with others as a recreational or social activity. The increasing popularity of swinging is regarded by some as arising from the upsurge in sexual activity during the sexual revolution of the 1960s. Swinging sexual activity can take place in a sex club, also known as a swinger club (not to be confused with a strip club).

Some people engage in various sexual activities as a business transaction. When this involves having sex with, or performing certain actual sexual acts for another person in exchange for money or something of value, it is called prostitution. Other aspects of the adult industry include phone sex operators, strip clubs, and pornography.

Legal issues
There are many laws and social customs which prohibit, or in some way have an impact on sexual activities. These laws and customs vary from country to country, and have varied over time. They cover, for example, a prohibition to non-consensual sex, to sex outside of marriage, to sexual activity in public, besides many others. Many of these restrictions are non-controversial, but some have been the subject of public debate.

Most societies consider it a serious crime to force someone to engage in sexual acts or to engage in sexual activity with someone who does not consent. This is called sexual assault, and if sexual penetration occurs it is called rape, the most serious kind of sexual assault. The details of this distinction may vary among different legal jurisdictions. Also, what constitutes effective consent in sexual matters varies from culture to culture and is frequently debated. Laws regulating the minimum age at which a person can consent to have sex (age of consent) are frequently the subject of debate, as is adolescent sexual behavior in general. Some societies have forced marriage, where consent may not be required.

Same sex laws
Many locales have laws that limit or prohibit same-sex sexual activity.

Sex outside of marriage
In the West sex before marriage is not illegal. There are social taboos and many religions condemn pre-marital sex. In many Muslim countries, such as Saudi Arabia, Pakistan, Afghanistan, Iran, Kuwait, Maldives, Morocco, Oman, Mauritania, United Arab Emirates,  Sudan, Yemen, any form of sexual activity outside marriage is illegal. Those found guilty, especially women, may be forced to wed the sexual partner, publicly beaten, or stoned to death. In many African and native tribes, sexual activity is not viewed as a privilege or right of a married couple, but rather as the unification of bodies and is thus not frowned upon.

Minimum age of sexual activity (age of consent)
The laws of each jurisdiction set the minimum age at which a young person is allowed to engage in sexual activity. The median age of consent seems to range from 16 to 18 years, but laws vary. In many jurisdictions, age of consent is a person's mental or functional age. As a result, victims can be of any chronological age if their mental age is below the age of consent. Many jurisdictions regard any sexual activity by an adult involving a child as child sexual abuse.

Age of consent may vary by the type of sexual act, the sex of the actors, or other restrictions such as abuse of a position of trust. Some jurisdictions also make allowances for young people engaged in sexual acts with each other.

Incestuous relationships
Most jurisdictions prohibit sexual activity between certain close relatives. These laws vary to some extent; such acts are called incestuous.

Sexual abuse
Non-consensual sexual activity or subjecting an unwilling person to witnessing a sexual activity are forms of sexual abuse, as well as (in many countries) certain non-consensual paraphilias such as frotteurism, telephone scatophilia (indecent phonecalls), and non-consensual exhibitionism and voyeurism (known as "indecent exposure" and "peeping tom" respectively).