Black, oolong and green teas come from the same plant, Camellia sinenis . The difference is that to make black tea, the leaves are dried, crushed and fermented. Crushing releases enzymes that oxidize the leaves, leaving them black. Oolong teas, such as jasmine, are oxidized for a shorter period of time, leaving them lighter in color, sometimes even red. Green tea leaves are steamed, rolled and then dried.
Tea drinking is an art form and integral part of the culture in much of Asia.
Green tea has grown popular in the west as evidence of its healing properties become validated by research. To me, a cup of hot green tea is soothing and refreshing. It gives my mind that extra burst of clarity and stamina I need for a long day of problem solving or writing. It is also comforting to know it may be reducing my risk of cancer and heart disease while perhaps enabling me to get away with snacking on a few of my favorites without gaining extra weight.