Pu-erh tea is made from the leaves and stems of the Camellia sinensis plant. Though the same source plant is used, the different teas are made by using different processes. After harvesting, the processing of pu'erh tea involves two stages. During the first stage, the leaves are prepared similar to green tea. During the second stage, the leaves undergo fermentation and then go into prolonged storage, or "aging," under high humidity. Pu-erh tea is used as medicine in many countries.