Tea is prepared by steeping dried tea leaves in boiling hot water to produce a homogeneous solution to drink. Since tea is based on naturally occurring plant leaves and the hot water readily dissolves many chemicals, a cup of tea contains hundreds of different chemical compounds dissolved in the water (not unlike coffee, beer, and wine). There are numerous types of teas but most teas do contain similar types of chemical compounds. Catechins are a major part of tea. These compounds are aromatic chemicals that usually function as anti-oxidants. Tea also contains amino acids including threanine, a mildly psychoactive substance that can affect dopamine levels in the brain. Tea also contains tannins, or large biological molecules that can impart deep color to tea. Finally, tea also contains numerous xanthines, or chemicals that can act as stimulants (like caffeine). This wide variety and diversity of chemical compounds in tea and other naturally derived beverages is what allows for their wide range of flavors and tastes. The antioxidants are what accounts for tea's health benefits.