The small intestine is a winding, tightly folded tube about
20 ft (6.1 m) long in adults.
It is connected to the stomach on the top end and to the large intestine
(colon) on the bottom end.
Most of the food a person consumes is digested and absorbed in the
small intestine. The lining of the small intestine has tiny finger-shaped raised
tissues (villi). These raised tissues greatly increase the surface area of the
intestine, which absorbs calories and nutrients from food.