Excluding water, tea is the most widely consumed drink on the planet, drunk either hot or cold by half the world’s population. The vast majority of tea sold in the West is black tea, made from fermented leaves of the Camellia sinensis plant. Generally stronger in flavor and more caffeinated than the green and oolong varieties, black tea retains its flavor for several years and has long been an article of trade, serving as a form of currency into the 19th century in what countries? Discuss
Source: The Free Dictionary