Tea is a natural beverage brewed from the leaves of an evergreen plant called Camellia sinensis. While it has become common place for people to refer to any hot beverage that is brewed from naturally occurring plants or plant extracts as "tea" technically, those herbal hot beverages should be called "teassanes", as the word "tea" is reserved for beverages brewed from leaves of Camellia sinensis.
The most widely consumed beverage, black tea is a close cousin to the Oolong in that if the tea is fermented long enough, the leaves turn black, hence the term "black tea". The exact time of rolling is determined by the size of the leaf, with smaller leaf being rolled for shorter period than larger leaf. Rolling induces fermentation of the leaf, and when the leaf is judged to be appropriately fermented, the process is slowed by allowing the leaves to cool off on ventilated trays for 3 to 4 hours. Finally, the fermentation process is stopped by drying the teas under hot blowers, at which point the tea leaves turn from reddish hue to black. The teas are then passed through various sieves to grade them.

Tea is a natural beverage brewed from the leaves of an evergreen plant called Camellia sinensis. While it has become common place for people to refer to any hot beverage that is brewed from naturally occurring plants or plant extracts as "tea" technically, those herbal hot beverages should be called "teassanes", as the word "tea" is reserved for beverages brewed from leaves of Camellia sinensis.
The most widely consumed beverage, black tea is a close cousin to the Oolong in that if the tea is fermented long enough, the leaves turn black, hence the term "black tea". The exact time of rolling is determined by the size of the leaf, with smaller leaf being rolled for shorter period than larger leaf. Rolling induces fermentation of the leaf, and when the leaf is judged to be appropriately fermented, the process is slowed by allowing the leaves to cool off on ventilated trays for 3 to 4 hours. Finally, the fermentation process is stopped by drying the teas under hot blowers, at which point the tea leaves turn from reddish hue to black. The teas are then passed through various sieves to grade them.