A threesome is a group of three engaged in the same activity. In relation to a sexual activity a threesome refer to the activity involving three people of any gender

Gender

Gender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...

 or sexual orientation

Sexual orientation

Sexual orientation describes a pattern of emotional, romantic, or sexual attractions to the opposite sex, the same sex, both, or neither, and the genders that accompany them. By the convention of organized researchers, these attractions are subsumed under heterosexuality, homosexuality,...

. A threesome should not be confused with a ménage à trois

Ménage à trois

Ménage à trois is a French term which originally described a domestic arrangement in which three people having sexual relations occupy the same household – the phrase literally translates as "household of three"...

, which is a long-term domestic arrangement involving three individuals, or a love triangle

Love triangle

A love triangle is usually a romantic relationship involving three people. While it can refer to two people independently romantically linked with a third, it usually implies that each of the three people has some kind of relationship to the other two...

.

Participating in or observing a threesome is a common sexual fantasy

Sexual fantasy

A sexual fantasy, also called an erotic fantasy, is a fantasy or pattern of thoughts with the effect of creating or enhancing sexual feelings; in short, it is "almost any mental imagery that is sexually arousing or erotic to [an] individual"...

 and has featured in several literary and film plots. Most of such threesome sexual activity is of a ménage à trois style; but pornographic films depict the sexual act more prominently and typically depicts one man and two women.

Types

There are a variety of sexual acts which can involve three participants.

Voyeurism - involves one participant participating as a spectator

Voyeurism

In clinical psychology, voyeurism is the sexual interest in or practice of spying on people engaged in intimate behaviors, such as undressing, sexual activity, or other activity usually considered to be of a private nature....

. Sometimes the spectator is there to enhance the experience of the active couple.

Soft-swinging - involves a person's sex partner watching while the person engages in sex with another person.

Double team - involves two participants engaging in sexual acts with a third participant, but not with each other. The non-participating members may, for example, be of the same sex. This arrangement may involve two active participants performing sex acts on one passive or submissive one. This may be a form of a gang bang

Gang bang

A gang bang is a situation in which one person has sexual intercourse and performs other sex acts with a number of people, either in turn or at the same time. When the person has not consented to such activity, it is called gang rape or pack rape.A limited study by Joan and Dwight Dixon indicate...

. For example, two men may both perform sex acts on a woman: one may be sexual intercourse

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 and the other anal sex

Anal sex

Anal sex is the sex act in which the penis is inserted into the anus of a sexual partner. The term can also include other sexual acts involving the anus, including pegging, anilingus , fingering, and object insertion.Common misconception describes anal sex as practiced almost exclusively by gay men...

 in a double penetration, or a woman/man may receive either intercourse and/or anal sex doggie style

Doggy style

Doggy style is a group of sex positions in which the receiving partner crouches on all fours with the legs slightly apart...

, while giving the third person oral sex

Fellatio

Fellatio is an act of oral stimulation of a male's penis by a sexual partner. It involves the stimulation of the penis by the use of the mouth, tongue, or throat. The person who performs fellatio can be referred to as the giving partner, and the other person is the receiving partner...

, or a man and woman may perform vaginal sex (from behind or reverse cowgirl), while a third person performs oral sex on the woman (clitoris

Clitoris

The clitoris is a sexual organ that is present only in female mammals. In humans, the visible button-like portion is located near the anterior junction of the labia minora, above the opening of the urethra and vagina. Unlike the penis, which is homologous to the clitoris, the clitoris does not...

) or on the man. There are many variations possible.

One active member - Another arrangement is for one active participant to perform sex acts on two passive or submission sex partners, either at the same time or consecutively. For example, one man may perform sex acts on two women, who do not interact with each other; or a woman may perform sex acts on two other individuals at the same time or consecutively.

Full threesome - involves each participants engaging in sex acts with the other two participants, though not necessarily at the same time.

Threesome sex between three men often involves one person both receiving and giving sexual stimulation. The receiving comes in the form of anal penetration and the giving is in the form of either oral stimulation or, in more adventurous circles, providing anal penetration to another party. The slang term for this middle person both receiving and giving anal sex is known as 'Lucky Pierre'.

Safety

Using condom

Condom

A condom is a barrier device most commonly used during sexual intercourse to reduce the probability of pregnancy and spreading sexually transmitted diseases . It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner...

s in a threesome may not be safe, it may transmit STDs including HIV

HIV

Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

. New condoms should be used with each partner. In case of two men and one woman having straight sex only male condoms are safe. And in case of one man having sex with two women then only female condom

Female condom

A female condom is a device that is used during sexual intercourse as a barrier contraceptive and to reduce the risk of sexually transmitted infections and unintended pregnancy...

s are considered safe.