The primary function of the small intestine is to complete the digestion of food and facilitate the absorption of nutrients. It is a long, coiled tube within the digestive system, consisting of three sections: the duodenum, jejunum, and ileum. After food passes from the stomach into the small intestine, enzymes from the pancreas and bile from the liver aid in breaking down carbohydrates, proteins, and fats. The inner lining contains villi and microvilli that increase the surface area for nutrient absorption into the bloodstream. This process is essential for providing energy and nutrition to the body.