Green tea is made by heating the harvested leaves as soon as possible to prevent fermentation. If tea leaves are left for a short while so that they lose some of their moisture and then heated, they will become half-fermented tea, that is oolong tea. If the leaves are not heated they become 100 per cent fermented. This tea, which has a distinctive aroma of fermentation, is black tea. So the degree of fermentation produces various types of tea. In the case of green tea, in Japan it is steamed first. After this the leaves are rubbed and then dried. During this process the leaves become twisted making today's cylindrical sencha. Bancha (coarse green tea) is heated once more before it is drunk is called hojicha (heated tea). For matcha (powdered green tea) the leaves are spread out for drying without first being rubbed. These are then ground and the veins and stalks separated from the rest of the leaves. The part left after the veins and stalks are thrown away is called tencha. This is then collected and ground in a mortar to make matcha.