What is the main function of the large intestine?

The primary function of the large intestine is to absorb water and electrolytes from the indigestible food matter that arrives from the small intestine. This process is crucial for maintaining the body's hydration and electrolyte balance. As the large intestine absorbs water, the remaining material becomes more solid and is transformed into feces.

Furthermore, the large intestine also plays a significant role in the fermentation of unabsorbed material by the gut microbiota, which contributes to the production of certain short-chain fatty acids and gases. While it does participate in some synthesis of vitamins through the actions of beneficial bacteria, the main and most critical function remains the absorption of water and the formation of feces. This function ensures that the body retains essential fluids while efficiently disposing of waste products, making it a vital component of the digestive system.