Black tea is a fully oxidized tea. Like all teas, black the is made from the Camellia sinensis plant.
Basically, there is a distinction between two black tea processing methods: CTC method (Crush Tear Curl) and Orthodox.
Orthodox is a traditional method in which the processing is done manually. The plucking is mostly done by hand. Usually only the youngest two leaves and a bud are plucked. Older leaves do not have all the subtle nuances of the younger shoots and would negatively affect the flavor.
Afterwards, the freshly harvested leaves are withered for several hours. This happens often in traditional bamboo trays. After withering the leaves are ready for the oxidation process.
To oxidize the leaves they are rolled to break up the cell walls and let the plant juice flow out. The later then reacts with the oxygen in the air. By oxidizing catechins are converted into theaflavins. As soon as the oxidation is finished, the tea leaves are dried to make them durable.
By CTC process as many operations as possible are performed mechanically. The leaves are chopped to achieve rapid oxidation and subsequent quick drying. The automated processes enables a economical production of tea. These teas do not have the quality of orthodox tea and are mostly used for tea bags.
Although black tea is now cultivated throughout the world, the most famous varieties still come from Asia.
Darjeeling in India is known for its high-altitude tea gardens. Especially popular with tea connoisseurs is the first flush of Darjeeling tea. Often these tea is flown in to ensure maximum freshness. This tea is called First Flush by Air.
Black tea from Assam is usually produced from the assamica tea plant and thus has rather a strong flavor. Assam is often found in tea bags and tea blends.
Keemun black tea originates from Anhui province in China and is considered as one of the best black teas and is a component of many tea blends. Lapsang Souchong originates originally from Fujian province and is known for its distinctive smoky flavor. The smoky flavor is achieved by smoking on smoldering pine roots. This tea is also found in many tea blends.