Oolong is a traditional Chinese tea somewhere between green and black in oxidation. It ranges from 10% to 70% oxidation.

      In Chinese tea culture, semi-oxidized oolong teas are collectively grouped as qngchá. Oolong has a taste more akin to green tea than to black tea: it lacks the rosy, sweet aroma of black tea but it likewise does not have the stridently grassy vegetal notes that typify green tea. It is commonly brewed to be strong, with the bitterness leaving a sweet aftertaste. Several subvarieties of oolong, including those produced in the Wuyi Mountains of northern Fujian and in the central mountains of Taiwan, are among the most famous Chinese teas.

      Ti Kuan Yin is a premium variety of Chinese oolong tea associated with Anxi in the Fujian province. Named after the bodhisattva Avalokitesvara (best known as Guan Yin), it has also been translated as "Iron Goddess of Mercy" after the old translation for Guan Yin's name.