All tea comes from a variation of the Camellia Sinensis plant. The differences between teas arise from processing it after it's picked, growing conditions, and geographic location.
The Camellia Sinensis plant is native to Asia, but is currently cultivated around the world in tropical and subtropical areas. With over 3,000 varieties, tea is the most consumed beverage in the world after water and also has a surprising number of health benefits.
White teas are the most delicate of all teas. They are appreciated for their subtlety, complexity, and natural sweetness. They are hand processed using the youngest leaves of Camellia Sinensis, with no oxidation permitted. When properly prepared, using shorter steeping times and a low temperature, white teas will produce slightly higher levels of caffeine than Green teas.
Green tea is permitted to barely wither after being picked. Then the oxidation process is stopped very quickly by flash heating the leaves. That way, green teas tend to have less caffeine (10-30% of normal coffee) if brewed properly. Green teas also tend to subtler flavors with lots of hints and touchesthat connoisseurs treasure.
Oolong tea (also called as wulong tea) undergoes a partial oxidation. These teas have a caffeine level between green and black teas. Oolong (wulong) tea flavors aren't usually as potent as blacks or subtle as greens, but have their own fragrant and intriguing tones. Many people compare the taste and scent of Oolongs (wulongs) to that of flowers or fruit.
Black tea is permitted to wither, which kicks off a process called oxidation (sometimes called fermentation) in which water evaporates from the leaf allowing the leaf to take in more oxygen from the air. Black teas usually undergo full oxidation, and the end result is usually a dark brown and black leaf. These are typically the more potent and strong flavors of black teas, and, when brewed correctly, a notably higher caffeine content when compared to other teas. Between 50% and 65% of a normal coffee, depending on the type of tea and the brewing style used.
Pu'erh is black tea from China, aged and prized for its perceived medicinal properties and hearty flavor. It's very strong with an incredibly deep and rich flavor, relatively little bitterness. Until 1995 Pe'erh wasn't permitted to be imported into the United States, and it's production methods continue to be a closely guarded state secret in China.