Tea, a popular beverage with its origins in southeast Asia, generally refers to an infusion derived from processed leaves, leaf buds, and internodes of the plant Camellia sinensis. There are four types of C. sinensis teas commonly available on the market - black, oolong, green, and white - which differ in their modes of processing, and in the case of white tea, maturity. (Red tea generally refers to an infusion derived from the South African Rooibos plant.) Green tea is produced from fresh leaves of the plant; unlike the black and oolong varieties, green tea is derived from fresh C. sinensis leaves that are steamed and dried at high temperatures before any oxidation and polymerization of polyphenolic compounds has taken place. © 2011 Springer- Verlag Berlin Heidelberg.