Caffeine is natural substance found in varying quantities in the beans, leaves, and fruit of over 60 plants, most known are coffee beans leaves tea.

It believed to have many effects on the body's metabolism, including stimulating the central nervous system.

Caffeine can also be produced synthetically and used as an additive in food products. It is in coffee, tea, chocolate, cocoa and drinks containing products derived from the kola nut.

Caffeine is frequently added to over-the-counter medications such as pain relievers, appetite suppressants, and cold medicines.