Your intestines are the long, coiled tubes in your belly that finish digesting your food and absorb the nutrients your body needs. After your stomach breaks down what you eat into a soupy mixture, your intestines take over the next steps.

You actually have two intestines working together. The small intestine comes first: it's about twenty feet long but coiled up to fit inside you, and it absorbs most of the vitamins, minerals, and energy from your food into your bloodstream. The large intestine (also called the colon) comes next. It's shorter but wider, and it absorbs water while preparing waste to leave your body.

Scientists sometimes call the intestines the gut or bowels. When doctors say someone has “intestinal fortitude,” they mean courage or determination, as if your guts themselves were brave. In older times, people believed your intestines were the source of strong feelings, which is why we still say things like “I had a gut feeling about it” or “that takes guts” when someone does something brave.

Your intestines contain trillions of helpful bacteria that aid digestion. Without this complex system working day and night, your body couldn't extract the nutrition it needs from food.