Pu-erh teas are aged and fermented. These aged teas are revered throughout Asia for their unique taste, and medicinal benefits. Pu-erh can be classified in two ways, dependending on how it is processed: The oldest method creates a Pu-erh that is called “Sheng” (raw). This traditional process involves compressing loose green tea into cakes. These cakes are slowly fermented over a very long period of time, usually from 10 to 50 years. When the cake is at least 30 years old, it is considered matured and given the label of “vintage.” In the 1970s a faster method of processing Pu-erh was invented. This Pu-erh is called “Shou” (cooked or ripe). The process is the same as in the Sheng variety but, before it is formed into bricks, the tea is exposed to rapid fermentation over 45 to 60 days to speed up the aging process. This expedited fermentation is done by putting the tea in piles that are then kept moist and hot to encourage beneficial yeasts and molds to grow. Once the fermentation is well underway, the tea is pressed into a variety of shapes.