The human body is an amazing machine, made up of many different parts. It is controlled by the brain, which is like a powerful computer. Messages between the brain and the rest of the body travel along nerves. The brain sorts information at high speed and sends messages to the rest of the body. The body is fueled by food and water. It needs exercise and rest to keep running at optimal speed. Skin is the largest part of the body and covers almost 21.5 square feet. Nerves live beneath the skin and send information to the brain at the slightest touch. Skin is like body armor that protects the heart.