The partially oxidized tea with a flavor between green and black tea is oolong.
Oolong is made from Camellia sinensis, the same species used for green, black, white, and yellow teas. Its defining distinction is processing: leaves are withered, bruised or rolled to encourage oxidation, then heated to stop that process. The result falls between minimally oxidized green tea and heavily oxidized black tea, although the category covers a broad range of styles.
Oxidation can range from about 8% to 85%, so oolongs vary dramatically. Light Taiwanese varieties may taste floral, creamy, or fresh, while roasted Wuyi teas from Fujian can have woody, toasted, or mineral notes. The leaves are commonly rolled into long strips or tightly curled beads.
A common mix-up is calling oolong “半-fermented” in a precise scientific sense. Tea makers generally mean partially oxidized; fermentation is not the main process. The name comes from the Chinese wūlóng, meaning “black dragon,” and was recorded for tea in an 1857 Fujian text. Oolong is especially associated with Fujian and Taiwan, where gongfu-style brewing uses repeated short infusions.