The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. In humans, the small intestine is further subivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum, colon and rectum.

The intestine is the part of the body responsible for extracting nutrition from food. While the stomach's role mainly consists in "breaking" food molecules into nutrients, the intestine allows these nutrients to enter the blood via its dedicated membrane. Ileus is a blockage of the intestines.

The small intestine has a particular folded texture in order to increase the irrigated exchange area where the nutrients can actually go through the membrane to the blood. It is an average 7 meters long.

The large intestine hosts several kinds of bacteria that deal with molecules the human body is not able to destroy itself. This is an example of symbiosis. These bacteria also account for the production of methane inside our intestine (known as flatulence when it is exhalated).