Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called polyphenols. Antioxidants are substances that scavenge free radicals -- damaging compounds in the body that alter cells, tamper with DNA (genetic material), and even cause cell death. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet rays from the sun, radiation, cigarette smoke, and air pollution) also give rise to these damaging particles. Scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.

Coming from the Chinese "wu"--"black"--and "lung"--dragon--the tea is more commonly termed "oolong" in the West--in fact, is considered the standard.The production of oolong requires that the leaves be processed directly after picking. First the leaves are wilted in the sun for a short period of time. They are placed into baskets and shaken, which bruises the leaves. The juices in the leaves are now exposed to the air, which begins the process of oxidation. The leaves are then spread out to dry. After a period of time--less than 2 hours for Chinese oolongs, longer for Taiwanese oolongs, the tea is fired, which stops the fermentation process.

While green tea usually loses its flavor within a year, black tea retains its flavor for several years. For this reason, it has long been an article of trade, and compressed bricks of black tea even served as a form of de facto currency in Mongolia, Tibet, and Siberia into the 19th century

White tea is tea manufactured by a process that uses relatively low heat and no rolling. The formative stage is an extended period of withering, during which enzymatic reactions progress under the right temperature, humidity and airflow. The key is to get the fresh leaves to mature properly with minimal oxidation.