Perspiration is a natural process that helps your body stay cool when it gets too hot. When your body heats up, it produces liquid called sweat. Sweat is made up of water, salt and other chemicals. Your body has millions of tiny little tubes called sweat glands that produce the sweat. When the sweat comes out of the glands, it sits on the surface of your skin, where it can cool you off. That's how perspiration helps you stay cool!