Anal sex or anal intercourse is a commonly practiced form of human sexual behavior in some cultures. It involves the anus and possibly the rectum, especially, but not limited to, the insertion of the erect penis into the rectum through the anus.
The use of sex toys and other activities involving the anus and rectum may be considered anal sex as well. Anal sex can be pleasurable for both the insertive partner and the receptive partner, as the anus contains many of the same kinds of nerves as the penis or clitoris.
For women, pleasure is derived from anal intercourse because the rectum shares a wall with the vagina and therefore shares some of the nerve endings associated with sexual pleasure. The anus itself also contains a number of nerves which can react pleasurably when excited.
For males, the tightness of the anus is often said to be a source of pleasure for the "active" partner in penetrative anal sex, while the presence of the prostate gland near the rectal wall is a source of pleasure during receptive anal intercourse. A sexual climax for the recipient (referred to colloquially as an anal orgasm) can occur through anal sex. Prostate stimulation can produce a "deeper" orgasm, sometimes described by men as more widespread and intense, longer-lasting, and allowing for greater feelings of ecstasy than orgasm elicited by penile stimulation only.
Women may sexually stimulate a man's anus by fingering the exterior or interior areas of the anus; they may also stimulate the perineum (which, for males, is between the base of the scrotum and the anus), massage the prostate or engage in anilingus. Sex toys, such as a dildo, prostate massager, or anal beads, may also be used. The practice of a woman penetrating a man's anus with a strap-on dildo for sexual activity is called pegging.
Commonly, heterosexual men reject the idea of being receptive partners during anal sex because they believe it is a feminine act, can make them vulnerable, or contradicts their sexual orientation (for example, that it is indicative that they are gay). National Institutes of Health (NIH) information published in the BMJ in 1999, however, states:
There are little published data on how many heterosexual men would like their anus to be sexually stimulated in a heterosexual relationship. Anecdotally, it is a substantial number. What data we do have almost all relate to penetrative sexual acts, and the superficial contact of the anal ring with fingers or the tongue is even less well documented but may be assumed to be a common sexual activity for men of all sexual orientations.
The vagina normally produces its own lubrication during sex; the rectum does not, so a store-bought personal lubricant is recommended by most sexologists for an enjoyable anal sex experience. According to the Centers for Disease Control and Prevention and the World Health Organization, unprotected anal sex carries more risk of STI transmission than vaginal or oral sex. To reduce the risk of transmitting STIs such as HIV, proper use of a latex condom is recommended for all sexual contact which could result in transfer of bodily fluids, including anal sex.
Note: If you are new to anal sex, remember to move slowly and gently. If it becomes painful, stop. It is possible to cause damage by too vigorous movement and moving too quickly. Always use lube! If you want to stop, make it clear to your partner that stop means stop beforehand.
Both men and women may find pleasure from anal stimulation. Men in particular will enjoy the anal orgasm so don't be put off exploring this area of your sexuality. Approach it correctly and enjoy!