Black Tea blends such as English Breakfast and Earl Grey are popular and they are available in tea bags at many shops. Loose leaf black teas however, are significantly more flavorful and aromatic.
India and Sri Lanka are some of the biggest producers of black tea. These countries mass produce in factories using industrial machinery using a method called CTC (Crush, Tear, Curl). This production method, however cannot preserve and develop the fine flavors of higher grade leaves. Majority of CTC production is for tea bags, where dust-like pieces of leaves called fannings are used. These fannings are lower quality leaves which are over oxidized due to higher surface area, and have lost much of their flavors and aromas.
Another way of processing and production is called the Orthodox method. This method preserves the whole leaf structure and therefore saves aromas and fragrances within the tea leaves. In India, Sri Lanka and Kenya black tea leaves produced by this method are ranked according to British grading system (Orange Pekoe, Flowery Pekoe etc.). However this method of grading is not common in China. All Chinese black tea are produced by the orthodox method.
Black tea manufacturing consists of plucking, withering, rolling, oxidation, drying and sorting. Oxidation is an important part of this process. The withered and rolled leaves are fully oxidized by spreading them on tables in humid environment for a period of time. Oxidation transforms the enzymes in leaves and this results in the black color as well as the astringency of this type of tea.