It is divided into two categories, green one and black one.
However, both of them are made of similar green leaves.
The difference of its colors are attributed to how to be made.
Heated earlier to prevent from being fermented, leaves keep green.
As a result, green tea contains much antioxidants such as catechin and vitamin C, which can keep you green too.
Actually it was originally introduced to Japan as a kind of medicines by Buddhist monks.
Green tea itself being easily oxidizable, you have to consume it in a good season or keep it in a freezer.
Fermented completely, leaves turn black.
Although black tea itself keeps longer, it doesn't keep you younger.
Speaking of ferment, we Japanese love fermented food such as natto, miso, soy sauce and so on.
Then, why don't we ferment tea?
That's another cup of tea.