Anal sex is a form of human sexual behavior. While there are many sexual acts involving the anus, anal cavity, sphincter valve and/or rectum, the term anal sex is often restricted to anal intercourse: the insertion of the erect penis into the rectum.
Anal sex is a vast subject, it includes a. insertion of penis into the anus (c.f. Anal Intercourse). b. stimulation of anal area with a sex toy by self or a partner (c.f. Anal Masturbation). c. stimulation of anus or anal area with a finger by a partner (c.f. postillionage). d.oral stimulation of anal area by a partner (c.f. anilingus).