Sexual intercourse, or coitus, refers in a strict biological sense to the insertion of the male's penis into the female's vagina for the purpose of reproduction. Sexual intercourse is found among all mammalian species.

Intercourse has traditionally been viewed as the natural endpoint of all sexual contact between a man and a woman. However, the meaning of the term has been broadened in recent years to include a wider range of behaviors and a wider set of motivations and intentions.

In both popular and professional usage, intercourse now labels at least three different sex acts, two of which are not directly tied to conceiving a child. These three types of intercourse are: vaginal intercourse, involving vaginal penetration by the penis, possibly to the point of male ejaculation and female orgasm; oral intercourse, involving oral caress of the sex organs (male or female), possibly to the point of orgasm; and anal intercourse, involving insertion of the male's penis into his partner's anus. The latter two of these behaviors may be the endpoints of a sexual encounter or they may be acts of foreplay leading to each other or to vaginal intercourse.

Moreover, intercourse is not limited to partnerships between individuals of opposite genders. Same-sex or homosexual encounters, involving oral or anal penetration or stimulation, are also referred to as sexual intercourse. Some also include digital (use of fingers or hands) intercourse or mutual masturbation as yet another form of intercourse.

Sexual Intercourse — The Most Intimate Behavior
In addition to recognizing a wider array of behaviors as constituting different types of intercourse, sex researchers and therapists have come to recognize that humans engage in sexual intercourse for many reasons beyond procreation. Sexual intercourse is among the most intimate behaviors possible between two people, and, for many people, it is also one of the most pleasurable and emotionally satisfying.

All of the types of intercourse mentioned above may produce orgasm for one or both partners. Orgasm is a complex physical and emotional release that can last from a few seconds to over a minute. Generally, it is followed by a significant sense of well-being and both physical and emotional relaxation.

While the experience of orgasm is generally similar among men and women, there are some differences. Male orgasm commonly follows a series of penile thrusts, rhythmic contractions of the prostate gland and the set of muscles surrounding the penis, testicle elevation, and ejaculation of semen from the penis. For almost all males, ejaculation is followed by a recovery period (that tends to grow longer with age) before it is possible to ejaculate again.

Female orgasm is variable, ranging from a single brief period of mildly pleasurable contractions of the uterine and vaginal walls to multiple episodes (approximately 0.8 seconds apart) of physically intense waves that cover the entire body and can last for long periods of time.

Copyright 2002 Sinclair Intimacy Institute