Puerh is a variety of post-fermented tea produced in Yunnan province, China. Post-fermentation is a tea production style in which the tea leaves undergo a microbial fermentation process after they are dried and rolled. This is a Chinese specialty and is sometimes referred to as dark, or black tea (this type of tea is completely different from what in West is known as "black tea", which in China is called "red tea"). There are a few different provinces, each with a few regions, producing dark teas of different varieties. Those produced in Yunnan are generally named Puerh, referring to the name of Puerh county which used to be a trading post for dark tea during imperial China. Puerh is available as loose leaf or in various compressed forms as a tea brick or cake.There is also the differentiation of cooked (shou) and raw (sheng) types.The shou type refers to those varieties that have gone through an accelerated post-fermentation process,while the sheng types are those in the process of gradual darkening through exposure to the environmental elements. Certain selections vary either type can be stored for maturity before consumption. That is why some are labeled with year and region of production.