A diagram of the large intestine, courtesy Connormah via Wikipedia
The large intestine, or colon, is a thick tube about ten feet long in humans that runs from the small intestine to the rectum. It's responsible for extracting nutrients and water from digested food that have not already been extracted in the small intestine.
The large intestine is shorter, thicker, and has a greater diameter than the small intestine. It's more resistant to injury, but also more susceptible to disease. Cancer of the colon and polyps are quite common.