braven wrote:What exactly is yellow tea?

Yellow tea is not really oxidized as was mentioned by other posters. The difference between yellow tea and early spring green teas is a single additional step in the processing called
men huan, which also defines this class of tea.
Yellow tea follows the same processing as green tea, except for the
men huan step. After plucking only buds or doing a
mao feng pluck of leaves in the early spring, yellow tea undergoes the same initial drying as green tea. However, right before the initial firing, yellow tea undergoes
men huan in which the leaves are slightly steamed and then covered by a cloth to bask in and absorb their own aromatics for several hours. Because it is steamed yellow tea really doesn't undergo oxidation more than the very small amount, if any, that green tea experiences.
The extra step is supposed to make yellow tea more mellow, unlikely to have a grassy or assertive taste and almost never having astringency. Anhui and Sichuan Provinces are the most famous for yellow teas. Yellow teas are some of the most rare because the
men huan is an expensive extra step and therefore that is why many in the West don't really know about this class of tea.