To create black tea, the leaves are plucked and then treated in this five step process.
Withering - Tea leaves are spread out in large groups and left to wither, losing some of their moisture.
Rolling - In the orthodox method, the leaves are now rolled so the remaining moisture is released, coating the surface of the leaves with its juices. This method is particularly gentle, so the tea leaves are usually left whole and unbroken. The CTC method, however, chops the tea leaves into tiny pieces, and you're left with a more dust-like substance.
Oxidation - The leaves are spread out again, this time in a cool, damp atmosphere, and the oxidation process continues. The color of a tea leaf is originally green, but as oxygen reacts with the cell tissues, it begins to turn a copper color. This is very similar to tree leaves turning from green to brown in the fall.
Drying - The leaves are dried with hot air, and the color changes from copper to brown or black.
Sorting - The final process involves sorting the tea leaves by size and grade.