Sexual behavior
Human sexual behavior or different human sexual practices encompass a wide range of activities such as the search for a partner or partners, interactions between individuals, physical or emotional intimacy, and sexual contact.
Some cultures will find only sexual contact within marriage acceptable; however, extra-marital sexual activity still takes place. Unprotected sex may result in unwanted pregnancy or sexually transmitted diseases. In some areas, sexual abuse of individuals is prohibited by law and considered against the norms of society.

# Aspects of human sexual behavior

## Cultural aspects
As with other behaviors, human intelligence and complex societies have produced among the most complicated sexual behaviors of any animal. Most people experiment with a range of sexual activities during their lives, though they tend to engage in only a few of these regularly. Most people enjoy some sexual activities. However, most societies have defined some sexual activities as inappropriate (wrong person, wrong activity, wrong place, wrong time, etc.) Some people enjoy many different sexual activities, while others avoid sexual activities altogether for religious or other reasons (see chastity, sexual abstinence). Historically, some societies and religions have viewed sex as appropriate only within marriage.

## Social norms and rules
Human sexual behavior, like many other kinds of activity engaged in by human beings, is generally governed 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, are illegal in some jurisdictions, including those conducted between (or among) consenting and competent adults (examples include sodomy law and adult-adult incest).  Scientific studies suggest sexual fantasy, even of unusual interests, is usually a healthy activity.
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, it is called prostitution. Other aspects of the adult industry include (for example) telephone sex operators, strip clubs, pornography and the like.
Nearly all developed societies consider it a serious crime to force someone to engage in sexual behavior or to engage in sexual behavior 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, precisely what constitutes effective consent to have sex 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 political and moral debate, as is adolescent sexual behavior in general.
It is possible to engage in sexual activity without a partner, primarily through masturbation and/or sexual fantasy.

## Frequency of sexual activity
The frequency of sexual intercourse might range from zero (sexual abstinence) to 15 or 20 times a week. It is generally recognized that postmenopausal women experience declines in frequency of sexual intercourse.. The average frequency of sexual intercourse for married couples is 2 to 3 times a week.
Sexual frequency often falls off in relationships when the initial period of limerence ends, and a common belief is that frequency of sexual intercourse often falls after marriage.  However, recent evidence shows that 43% of married couples have sex a few times a month, as compared with 36% of cohabiting couples.

# Safety and ancillary issues
There are four main areas of risk in sexual activity, namely:
- choosing to trust a partner who is physically at risk
- sexually transmitted disease
- unwanted pregnancy
- seeking or engaging in an activity which is legally or culturally disapproved
These risks are raised by any condition (temporary or permanent) which impairs one's judgement, such as excess alcohol or drugs, or emotional states such as loneliness, depression or euphoria (e.g. new students at college). Carefully considered activity can greatly reduce all of these issues.

## Sexually transmitted disease
Sexual behaviors that involve contact with another person or the bodily fluids of another person entail some risk of transmission of sexually transmitted disease. These techniques are generally seen as less necessary for those in committed fidelitous monogamous or polyamorous relationships with persons who have been demonstrated to be free of disease; see fluid bonding.
Due to health concerns arising from HIV/AIDS, chlamydia, syphilis, gonorrhea, HPV and other sexually transmitted infections, some people may want potential sex partners to be tested for STDs before engaging in sex.

## Unwanted pregnancy
Sexual behaviors that involve the contact of semen with the vagina or vulva may result in pregnancy.  To prevent pregnancy, many people employ a variety of birth control measures. The most popular methods of prevention are condoms, spermicides, hormonal contraception, and sterilization.

# Legal issues related to sexual behavior

## Sodomy and same sex laws
Various forms of same-sex sexual activity have been prohibited under law in many areas at different times in history. In 2003, the Lawrence v Texas United States Supreme Court decision overturned all such laws in the US.
Usually, though not always, such laws are termed sodomy laws, but also include issues such as age of consent laws, "decency" laws, and so forth. Laws prohibiting same-sex sexuality have varied widely throughout history, varying by culture, religious and social taboos and customs, etc. Often such laws are targeted or applied differently based on sex as well. For example, laws against same-sex sexual behavior in England during the reign of Queen Victoria, sodomy or "buggery" laws were aimed specifically at male same-sex sexual activity and did not target or even address female homosexuality. A well known example of such laws applied in modern times can be found in Alan Turing.

# Child sexual abuse

# List of sex acts and practices

## General
- Barebacking
- Erotic massage
- Erotica
- Group sex
- Sex toy
- Cunnilingus
- Fellatio
- Anilingus
- Sexual fantasy
- Masturbation
- Oral sex
- Oral stimulation of nipples
- Sexual Intercourse
- Anal Intercourse
- Intercrural sex
- Outercourse
- Pornography
- Roleplay
- Sex positions
- Foreplay

## BDSM-related
- BDSM
Bondage
List of bondage positions
Domination and submission
Sadomasochism
Impact play
- Bondage
- List of bondage positions
- Domination and submission
- Sadomasochism
- Impact play
- Fetishism
Foot fetishism
Leather fetishism
Latex and PVC fetishism
- Foot fetishism
- Leather fetishism
- Latex and PVC fetishism
- Nyotaimori
- Wax play

## Specialized verbal or visual activities
Some forms of sexual activity involve someone else, but not touching the other:
- Dirty talk
Phone sex
Cybersex
- Phone sex
- Cybersex
- Exhibitionism is the recurrent urge or behavior to expose one's genitals to an unsuspecting person.
- Voyeurism is the recurrent urge or behavior to observe an unsuspecting person who is naked, disrobing or engaging in sexual activities.