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. In fact, the English so enjoy their tea that they developed a meal around it, high tea. 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.
All tea plants belong to the same species but varying climates, soils, etc.
The processing of those leaves is responsible for the individual characteristics of each tea. 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. Although black tea flavors vary, most are more assertive than those of green or oolong teas.