The colon is part of the large intestine, the final part of the digestive system. Its function is to reabsorb fluids and process waste products from the body and prepare for its elimination. The colon consists of four parts: descending colon, ascending colon, transverse colon, and sigmoid colon

While the small intestine plays a major role in absorbing nutrients from food, the large intestine plays a much smaller role. It stores waste, reclaims water, maintains water balance, absorbs certain vitamins (like vitamin K), and provides for flora-aided (mostly bacterial) fermentation.

The descending colon is located on the left side of the large intestine, extending from the bend below the spleen to the sigmoid colon. The descending colon stores the food to be emptied into the rectum. The colon is held in place by peritoneum, a thin layer of tissue that supports the abdominal organs. Blood vessels, lymph vessels, and nerves all pass through the peritoneum to reach various organs.