As a general rule:
Tea has about half the caffeine of coffee per cup.
Black teas are high in caffeine,
green teas are lower and
white teas are the lowest.
Decaffeinated teas have had the caffeine removed.
All true teas come from the camellia senensis plant.
Black tea leaves are fermented (oxidized) Black teas leaves are fermented in cool, humid rooms, until the entire leaf is darkened
Oolong (also known as red tea) is partially fermented The leaves of Oolong tea are wilted in sunlight, bruised and allowed to partially oxidize, until reddening of the leaf edges occurs.
Green tea the leaves are not Green tea leaves are allowed to wither in hot air then pan-fried to halt the oxidation (fermentation) processes.
White tea is the least processed of all tea. The only processing that the leaves undergo is being steamed / heated to prevent oxidation.
