Pu-erh tea (Chinese 普洱茶) is a fermented tea, named after Pu Erh in Yunnan, China. It is an unusual black tea, because as opposed to other teas which are consumed shortly after production, it can be over 50 years old. Over this time they acquire an earthy flavour due to the layer of mold that develops on the leaves (or tea brick if they are compressed). The tea is often steeped for long periods of time and can acquire a dark brown/black color, as dark as strong coffee.
In Cantonese culture, pu-erh is known as po-lay or bo-lay tea, and is often drunk during dim sum meals with family and friends, as it is believed to help with digestion. Pu-erh is considered a medicinal tea in China.