Caffeine is an alkaloid found in coffee, tea, chocolate, and other natural foods. It is also a component of cola soft drinks. Caffeine has been a part of the human diet for many centuries and is one of the most widely used central nervous system stimulants in the world. In recent years, research has raised questions about possible deleterious health effects of caffeine, but no definitive conclusions have been reached about the harmfulness of moderate amounts.

Caffeine's chemical name is 3,7-dihydro-1,3,7- trimethyl-1H-purine-2,6-dione. It is also known as theine, methyl theobromine, and 1,3,7-trimethylxanthine. Its molecular formula is C ₈H ₁₀N ₄O ₂ H ₂O, and it consists of bicyclic molecules derived from the purine ring system.

In its pure form, caffeine is a fleecy white solid or long silky crystals. It is odorless, but has a distinctive bitter taste. When heated, caffeine loses water at 176°F...