Tea is a natural beverage brewed from the leaves of an evergreen plant called Camellia sinensis. While it has become common place for people to refer to any hot beverage that is brewed from naturally occuring plants or plant extracts as "tea" technically, those herbal hot beverages should be called "teassanes", as the word "tea" is reserved for beverages brewed from leaves of Camellia sinensis.

The camelia sinensis is a very versatile plant that can grow under almost any conditions. Thus, tea is grown around the world from the Indian Sub-continent in India, Nepal, and SriLanka, to China, Japan, Indonesia, Vietnam, to the African subcontinent in Kenya, to Latin America in Argentina. As can be imagined, the quality of tea varies dramatically from region to region, with most of the variations originating in the variation in the climactic conditions of the regions where the tea is grown and not from the differences in the tea bush itself.
The largest difference in flavor of teas comes from the altitude at which the tea is grown and the type of soil the bush is grown in. High growth teas tend to be far superior to the lower growth regions with respect to the subtelities of flavor, color and fragrance. This is because high altitude tea gardens often provide cool temperatures and higher rainfall, resulting in the slower growth of the bush. Often, the number of bushes that can be planted along the slopes is also limited (compared to on flat ground) resulting in less competition for resources. As a result, the high altitude gardens often produce a more flavorful tea although the yields of these gardens are often lower than the lower altitude gardens. Shade grown tea are also more flavorful than the teas grown in full sun, for much the same reason why high altitude teas are more flavorful than low altitude teas.