Tea is native to China, where it grew wild until the Chinese determined that the leaves helped flavor the flat taste of the water they boiled to prevent getting sick. Tea plant cultivation in China began about 4,000 years ago but it wasn't until the 8th century A.D. that outsiders (the Japanese) discovered it. Europeans were finally introduced to tea during the 17th century and the British (who were the true tea lovers) spread its use by implementing new growing areas such as India. In fact, the English so enjoy their tea that they developed a meal around it, high tea. Tea also played an important role in the development of the United States its taxation led to the Boston Tea Party, one of the issues that triggered the War of Independence. Americans further influenced tea use both by inventing tea bags and by starting the practice of drinking iced tea at the St. Louis World's Fair in 1904. The word "tea" can refer to the beverage, the leaves used to make the beverage and the magnolia-related evergreen shrub from which the leaves come. All tea plants belong to the same species but varying climates, soils, etc., combine in different ways to create a plethora of distinctive leaves. The processing of those leaves is responsible for the individual characteristics of each tea. Leaves are sorted by size those that are young and tender are superior to older, coarser leaves. Black, green and oolong tea are the main types produced during processing. Black tea comes from leaves that have been fermented before being heated and dried. Such leaves produce a dark reddish-brown brew. Black teas are graded according to the size of the leaf; orange pekoe describes leaves that are smaller than the medium-size coarser pekoe leaves. Although black tea flavors vary, most are more assertive than those of green or oolong teas. Among the more well-known black teas are darjeeling, English breakfast and lapsang souchong. Green tea, favored among Asians, is produced from leaves that are steamed and dried but not fermented. Such leaves produce a greenish-yellow tea and a flavor that's slightly bitter and closer to the taste of the fresh leaf. Two of the more well-known green teas are tencha and gunpowder. Scientific studies have shown that black and green teas increase the body's antioxidant activity by up to about 45 percent. They are also said to have antibacterial powers against cavities and gum disease. Oolong tea is produced from leaves that are partially fermented, a process that creates teas with a flavor, color and aroma that falls between black tea and green tea. The best known oolong is formosa oolong, from Taiwan. In addition to these three main types of tea there are specialty teas. Such teas are flavored with various floral or spice additions such as jasmine or chrysanthemum blossoms, or orange or lemon peel. Instant tea, which dissolves quickly in cold or hot water, consists of brewed tea that is dehydrated and granulated. It often contains sugar or sugar substitutes and other flavorings such as cinnamon or lemon. Herb tea is not a true tea based on tea-shrub leaves, but rather an infusion of various herbs, flowers and spices. Both black teas (in leaf and tea-bag form) and instant teas are readily available in most supermarkets. Other teas can be found in great variety in natural food stores, Asian markets and stores specializing in tea and coffee.