Chai teas are usually highly spiced and flavored black teas. Some are meant to be brewed extremely strong and astringent. These should tempered through the use of milk and sugar.
Indian and Kenyan black tea, ginger, cinnamon, cardamom, black and white pepper, clove and nutmeg.
Sri Lankan black tea, coriander, cumin, sweet fennel, cinnamon, cardamom, curry, and lemongrass leaves.