What is Caffeine?

This may seem like a ridiculous question but most people only know that caffeine is a chemical in coffee that gives you a lift. Caffeine is not as simple as it seems. Chemically it is an alkaloid stimulant naturally occurring in the coffee beans, which contain a rough average of about 4% caffeine in proportion to their weight. Strangely while caffeine stimulates your heart and lungs it actually relaxes your digestive system.