How Is Tea Made Into Green and Black Tea?

All true tea comes from the leaves of Camellia sinensis. For green tea, freshly picked leaves are steamed (common in Japan) or pan-fired (common in China) soon after plucking, which deactivates the enzymes that cause browning. For black tea, leaves are withered, rolled to break their cells, and left exposed to air so they oxidise and darken. Oolong tea is partly oxidised, sitting between the two. The leaves are then dried to preserve them, and each processing style creates very different flavours.