Caffeinated teas come from a single tea plant, camellia sinensis, processed in different ways to yield different teas, such as green, oolong and black teas.
Green Tea - leaves immediately dried after picking and rolling, which retains most of the bright color of fresh leaves. Methods of drying include steaming, roasting, and baking. Common green tea flavor profiles are a fresh vegetal green, and can be sweet, bright, savory, grassy, and smoky.
Oolong Tea - processing method in between green tea and black tea. Leaves are partially oxidized, allowing for changes in flavor and leaf color. Flavor profiles vary widely because of this oxidation process, from complex floral, sweet, or fruity notes to deeper flavors- smoky, nutty, earthy, caramel, toast.
Black Tea - fully oxidized, allowing flavors to change and deepen. Black teas have a rich flavor range similar to more highly oxidized oolong teas: earthy, nutty, malty, musky, caramel, leather, and can have lighter undertones as well that are fruity or sweet. Black tea also has the highest concentration of tannins, which gives it a brisk, astringent texture.
Herbal Tea - naturally caffeine-free, made from any range of plants outside of camellia sinensis. Some of the more popular herbal teas are made from common herbs and spices, such as mint, chamomile, ginger, lemon balm, and lemongrass.
Rooibos is a popular herbal tea. Red rooibos is made from oxidizing the leaves of this South African red bush plant. It's a great caffeine-free alternative to black tea, often consumed with milk or lemon and honey.