Tea

Tea is a slightly bitter aromatic beverage produced by the infusion of tea leaves in hot water. Tea leaves are the processed leaves and buds of the subtropical bushy plant Camellia sinensis, which is native to southeast Asia. Tea is the second most common drink in the world, behind only water. A variety of C. sinensis called Assamica is responsible for tea from Assam in northeastern India.

The origins of tea drinking are unknown, but probably started in the 10th century BCE in China, and became popular there by 200 BCE. Tea drinking spread to Korea and Japan (where elaborate ceremonies grew up around tea consumption), and then to Europe in the 16th century. As tea plants need around 50 inches of rain a year to produce, and grow higher quality leaves in high altitudes, most tea comes from China and India. 

The best teas are identified with a system of abbreviations, and typically with the name of the plantation it came from. Sometimes labels might include a long acronym like TGFOP, which indicates a Tippy Golden Flowery Orange Pekoe tea, with a predominance of young tips, buds and large leaves. Orange Pekoe is a bit confusing, and may refer to the coppery color from oxidation and downy hairs on the underside of high quality, early season picked tea leaves.

Only the top one to two inches of a tea plant are harvested at any given time, in waves called "flushes". Once the leaves are picked, enzymatic changes in the leaves lead to oxidation, which is called fermentation (though it is not an alcoholic fermentation at all). This change can be halted by heating the leaves, and the combination of wilting and oxidation change the color and flavor of the resulting leaves. Tea leaves can be broken down into six major categories:

• Green - Unwilted and unoxidized. Green teas taste grassy, herbal, and fresh.
• Yellow - A rare type of tea that is between green and white. Partially wilted and unoxidized.
• White - Wilted and unoxidized. The most delicate of teas, with floral aromas and delicate flavors.
• Oolong - A halfway style wilted and partially oxidized
• Black - The most common style. Wilted and oxidized until very dark. 

Other plant leaves (such as roobois), herbs (such as mint or chamomile) and dried fruits can be infused into hot water. While technically, these are not teas, they are commonly named as such. A style of tea called Pu-erh undergoes extensive microbial action post drying, and can be compressed into cakes or other forms, then stored, sometimes for decades, developing a rich, compost-like aroma and flavor.

Both the temperature of the brewing water and the amount of time the leaves are in contact with the hot water will dramatically affect the flavor profile of tea. Typically, the lighter the tea, the lower temperature and less time it needs to extract flavors. Darker teas can withstand temperatures near boiling, and longer infusion times. High quality teas can withstand multiple infusions of water which give different flavor profiles in the cup. Tea should never be brewed for maximum extraction, and overbrewing tea leads to unpleasant bitter flavors. 

Tea is also commonly flavored. Flavored teas can be as simple as placing dried flowers in with the tea, such as jasmine tea, or as complex as adding flavoring oils (like Earl Grey, flavored with bergamot oil), dried fruits, herbs or spices. Teas can be smoked and dried over pine fires like Lapsang Souchong. In India, chai is prepared with cloves, cinnamon sticks, cardamom, peppercorns, and ginger in addition to tea leaves and served sweet and milky. One interesting Japanese take is genmaicha, which is green tea with the addition of puffed rice. Post-brewing, tea can also be flavored with milk and sugar. 

Tea contains a type of antioxidant called catechins, along with caffeine, theobromine, and theophylline. All things being equal, a cup of tea has less caffeine than a cup of coffee, though by weight, tea leaves contain more caffeine than coffee beans. While tea can have a bitter flavor, it does not contain tannic acid.