Black tea is a type of tea that is more oxidized than Oolong, green and white teas. All four types are made from leaves of the shrub Camellia sinensis. Black tea is generally stronger in flavor than the less oxidized teas. Two principal varieties of the species are used-the small-leaved Chinese variety plant,used for most other types of teas,and the large-leaved Assamese plant, which was traditionally mainly used for black tea,although in recent years. some green and white have been produced. 

In Chinese languages and the languages of neighboring countries, black tea is known as"red tea", a description of the color of the liquid; the Western term "black tea"refers the the color of the oxidized leaves. In Chinese, "black tea" is a commonly-used classification for post-fermented teas, such as Pu-erh tea; outside of China and its neighboring countries, "red tea"more commonly refers to rooibos, a South African tisane.  

While green tea usually loses its flavor within a yea, black tea retains its flavor for several years. For this reason,it has long been an article of trade, and compressed bricks of black tea even served as a form of de facto currency in Mongolia, Tebet and S iberia into the 19th century.Although green tea has recently seen a revival due to its purported health benefits, black tea still accounts for over ninety percent of all tea sold in the West.