In humans, the large intestine begins in the right iliac region of the pelvis, at the waist or below the waist, where it is joined to the end of the small intestine at the cecum, via the ileocecal valve. It then continues as the colon ascending the abdomen, across the width of the abdominal cavity as the transverse colon and then descending to the rectum and its endpoint at the anal canal.
The colon is the last part of the digestive system. It extracts water and salt from solid wastes before being eliminated from the body and is the site in which flora-aided (largely bacterial) fermentation of unabsorbed material occurs.
The major function of the large intestine is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body.
Constipation, the unusually sluggish transit of fecal materials through the colon that causes the infrequent passing of hard feces, is both cause and symptom.