In anatomy, the anus is the external opening of the rectum. Closure is controlled by sphincter muscles. Feces are expelled from the body through the anus during the act of defecation, which is the primary function of the anus. Most animals — from simple worms to elephants and humans — have a tubular gut, with a mouth at one end and an anus at the other.
The anus is often considered a taboo part of the body, and is also known by a large number of slang terms, which are generally considered vulgar and not used in polite speech.