The most common tea in the United States, black tea is made from tea leaves that have been allowed to fully oxidize. The result is a tea that gives a reddish-brown infusion with sizeable body and power in the cup. The individual cup character fo black teas depends, of cours, on the region where it was grown, that season's climatic conditions, and the specific varietal from which the leaves are plucked.
To make black tea, the leaves are first allowed to wither after harvesting and are then rolled to start the oxidation process. Then the leaves are spread out and allowed to fully oxidize. At this point, the leaves turn a coppery red. The process is completed by firing and drying to halt the oxidation and to stabilize the tea leaves.
Black Teas are often referred to as orthodox or CTC (cut-tear-curl), depending on their specific manufacturing process. Orthodox teas are produced in the traditional fashion, whereas CTC teas have been minced and curled into little balls by specialized machiner. Relatively good CTC teas can be found, but they're typically of lower quality than high-quality orthodox teas. Bagged blackteas are commonly made from CTC teas.