Black tea is what most North Americans think of when the word "tea" comes to mind. Many in the western world drink black tea as the British do, by adding milk.
Black tea is the most oxidized of the tea varieties, contains the most caffeine, and has the strongest flavour. As with most of the other tea varieties, black tea comes from the camellia sinesis plant. Two principal varieties of the species are used: the first is the small-leaved Chinese variety plant (camellia sinensis sinensis) which is also used for green and white teas. The second, a large-leaved Assamese plant (camellia sinensis assamica) which was traditionally only used for black tea.
In countries like China, black tea is actually known as "crimson or red tea" because of the actual colour of the tea once it has been brewed, while teas such as pu-erh, a post-fermented tea, are known as "black teas". However, in the western world, "red tea" is commonly known as rooibos tea, a herbal tea which comes from South Africa.
While green tea usually loses its flavor within a year, black tea retains its flavour for several years. For this reason, it has long been an article of trade. Compressed bricks of black tea even served as a form of de facto currency in Mongolia, Tibet, and Siberia into the 19th century.
The tea originally imported to Europe was either green, or semi-oxidized. Only in the 19th century did black tea surpass green in popularity. 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.
In North America, black tea is steeped at around 99 °C (210 °F), but lower temperatures are used for more delicate black teas. Many of the active substances in black tea do not develop at temperatures lower than 90 °C (194 °F). It is also recommended that the teapot be warmed before preparing tea, easily done by adding a small amount of boiling water to the pot, swirling briefly before discarding. In the West, black teas are on average brewed for about 4 minutes and are usually steeped for a minimum of 30 seconds and a maximum of 5 minutes to avoid bitterness due to oversteeping. However, in many regions of the world, boiling water is used and the tea is often stewed. For example, in India black tea is often boiled for fifteen minutes or longer as a strong brew is preferred for making masala chai.
