Caffeine is a chemical compound called 1,3,7-trimethylxanthine, which is found in specific plants. It stimulates the central nervous system and works as a psychoactive drug, raising alertness and improving the user's perception of well-being. It is available in a variety of forms, the most common ones being coffee beans and tea leaves.
Of the many species of coffee plants, the most important to the commercial industry are arabica and canephora. Arabica descended from an original species of coffee found in Ethiopia. It produces a flat, long bean that is slightly less caffeinated than the bean of the Canephora tree, also known as robusta. Robusta grows in warmer climates such as Africa and Southeast Asia, including Indonesia, Vietnam and also Brazil. Coffee trees produce coffee cherries after flowering. The cherries -- or beans -- are harvested after they mature, which can take up to a year. Coffee beans can be grown, roasted or blended to produce a variety of tastes.
All varieties of traditional caffeinated tea comes from a plant called Camellia sinensis. Tea growers havest the leaves and process them to produce different types and flavors. The level of oxidation determines the type of tea; among the caffeinated varieties are green, white, black and yellow. In 2010, Americans consumed over 65 billion servings of tea, according to the Tea Association of the U.S.A. About 80 percent of all tea consumed was black tea and 19.5 percent was green tea.
Caffeine in certain soft drinks ranges from 24 to 54 mg per 12 oz. drink, according to research from Mayo Clinic. The caffeine in soft drinks is chemically identical to the caffeine found in coffee and tea, though it has been purified to a powder or produced synthetically to add to the drink.
Energy drinks are becoming another popular way to consume caffeine. The average popular energy drink has more caffeine per ounce than soft drinks, created with the intention of giving the user a short-term boost of energy.
Caffeine is also present in certain pain relievers. Caffeine helps the body absorb the analgesic portion of the medicine, which is the active painkiller in the drug. This enables the painkillers to be more effective in smaller doses. The amount of caffeine in over-the-counter drugs is required to be on the label.