More than just tea in a bag! Black tea is the most popular type of tea in western countries. Maybe because it has a longer storage life than green, white or oolong tea, so was better suited for the long transport time during the early days of European / Asian trade.
To produce black tea, the leaves undergo more oxidation when compared to green, white, oolong teas. This not only results in darker tea leaves, but also a stronger and more intense taste.
The most popular method of serving Black Tea in the West is adding milk or sugar to reduce the natural astringency and bitterness of Black Tea, but In China and other parts of Asia, it is usually served straight.
Among Black Tea we can count outstanding and rare varieties. The premium tea ages well and improves over time. The best whole leaf Black Teas are made by hand, in contrast to the commercial CTC (Crush-Tear-Curl) of tea-bags.
Also, don't forget the Health Benefit of Black Tea. A long-term study by the Netherlands National Institute of the Public Health and the Environment found a correlation between regular consumption of black tea and reduced risk of stroke.