No matter what kind of tea you drink-black, green, or oolong-each shares components that affect how you feel and what you taste and smell. The main components of tea are caffeine, polyphenols (tannins), and essential oils.

Tea's pleasant lift comes from caffeine, a mildly habit-forming drug appearing naturally in many plants (tea, coffee, and cocoa, to name a few). People who drink tea often boast to their coffee-loving rivals that their beverage has half the caffeine of that high-octane bean. Sorry folks, that's not the case, but you can still feel smug. Let me explain. By weight, in its dry form, a pound of black tea has twice the caffeine as the same amount of coffee. What's the catch? You make two hundred cups from a pound of tea and only forty cups per pound of coffee.

The amount of caffeine in tea depends on the plant and the way it is processed. Fermentation also increases the amount of caffeine that makes its way to your cup. Since green tea is not fermented, it has the least caffeine. Here's a quick comparison: A six-ounce cup of drip coffee contains 70 to 180 milligrams of caffeine; a six-ounce cup of black tea has 25 to 110 milligrams, while oolong contains 12 to 55 milligrams, and green tea has 8 to 16 milligrams. To learn more about caffeine in tea, how it affects your body and your health, and ways to cut down, check out the next section, "Tea and Health."

A tea s color, pungency, and body come from polyphenols, also referred to as tannins. These components are present in every leaf, but the tender new growth, consisting of two leaves and a bud, is almost three times richer in Polyphenols than the older leaves.

During fermentation, some of the polyphenols are oxidized and become water soluble. These polyphenols give tea its distinctive color. The unoxidized polyphenols, those that are not fermented, give tea its pungency. Because green tea is not fermented and its polyphenols are unoxidized, it is pale and has less body than black or oolong, but it tends to be more pungent. On the other hand, fermented black tea gets its rich, amber color from the oxidized polyphenols and, because it has fewer unoxidized polyphenols, is less pungent than green tea. As with much of life, however, generalizations don't tell the entire story.

The essential or aromatic oils give tea its fragrance and flavor. The oils are also known to aid in digestion because they stimulate peristalsis. In green tea, the flavor comes from the unfermented oils. In black tea, it comes from oils changed during oxidation. Therefore, in oolong tea, the fragrance and flavor come from a combination of unfermented and fermented oils. When these essential oils come into contact with your brewing water, they evaporate, giving you their elusive gift. When you brew a cup of tea properly, the caffeine, polyphenols, and essential oils interact and combine to make a tantalizing drink that, next to water, is the most popular beverage on earth.