Anal sex is a form of human sexual behavior which encompasses many sexual acts involving the anus, anal cavity, sphincter valve and/or rectum. The term anal sex, however, is often restricted to anal intercourse: the insertion of the erect penis into the rectum.[1]
It is a form of sexual behavior considered to be comparatively high in risk, due to the vulnerability of the tissues and the septic nature of the anus.[2] As the rectal mucosa provides little natural lubrication, a lubricant (such as a personal lubricant, for example) is most often required or preferred when penetrating the anus.
