This category of tea is unique in that it undergoes fermentation. In fact, for pu’er tea, the panfryng does not completely eliminate the enzymatic activity, but a part of it is left alive, so that over the years the leaves ferment and develop unique flavors. Pu’er tea is divided into two categories: “Sheng” (= raw), if the fermentation occurs naturally over the years, or “Shu” (= cooked), if the fermentation is speeded up by putting the leaves in peculiar conditions of humidity and temperature, so that in a few months the leaves reach a fermentation level that would take tens of years to occur naturally. Pu’er tea takes its name from the city of Pu’er, in Yunnan, China, where the most important commercial exchanges of this tea took place, and therefore indicates the fermented tea of this region. But it is possible to find similar products in other Chinese regions such as Anhui, for which the more general term “Hei cha”, black tea, is used.