Of all teas, black tea is the most consumed tea in the world today. It is also popular because some people believe that its has a very pleasant smell. With black teas, they are truly the most common on all markets in the world. Darjeeling, Assam, Ceylon, and Keemun are a few of the most well known. These teas are heavily oxidized and brew up strong, bold, and often malty. Unlike white, green, or oolongs, processed black teas are separated into a grading system. For example, Orange Pekoe (OP) means full-leaf tea, and BOP indicates a broken leaf black tea. In general, the more crushed/broken the leaf, the stronger the brew. Black teas serve as the base of popular scented teas including Earl Grey. In China, black tea is referred to as red tea because of its color once brewed.

Moreover, tea is the most popularly manufactured and consumed drink in the world, equaling all others – including coffee, chocolate, soft drinks, and alcohol – combined. It is the second most popular drink in the world after water. Tea is now part of a $10 billion dollar worldwide industry.

More Info: en.wikipedia.org