The role of the large intestine in digestion involves the reabsorption of water and the formation of feces. This organ helps to consolidate waste that is left after nutrients have been absorbed in the small intestine. The large intestine also houses a variety of microorganisms that aid in the fermentation of remaining undigested materials, producing vitamins and further breaking down substances. Ultimately, it prepares waste for excretion from the body, playing a vital role in maintaining fluid balance.