Black tea is what most people envision when they think generally about "tea." Its most popular incarnations come from India (Assam, Darjeeling), Sri Lanka (Ceylon), and China (Lapsang souchong), and some of the world's favorite teas, including Earl Grey and English Breakfast, are blends of black teas. Black tea has the highest caffeine content of the major types of tea, though it still only has half the caffeine of coffee. It is best enjoyed with a hint of sugar or honey, and a bit of lemon or milk.
Black tea is fermented, meaning that freshly-picked tea leaves are allowed to oxidize and develop deep flavors. This fermentation process alters the antioxidants that are naturally found in tea leaves, which are called flavonoids. The flavonoids found in black tea are more complex than those found in less processed teas, but in any kind of tea, antioxidants are believed to have health benefits including cancer prevention, cholesterol reduction, and protection against stroke and heart attack. Black tea also is rich in manganese and potassium, and it contains some B-vitamins.