A tandoor is a cylindrical clay oven used in cooking and baking. Temperatures in a tandoor can approach 480°C (900°F), and it is common for tandoor ovens to remain lit for long periods to maintain the high cooking temperature, says Wikipedia.
Tandoori chicken is a roasted chicken delicacy which is marinated in a yogurt seasoned with garam masala, garlic, ginger, cumin, cayenne pepper, and other spices depending on the recipe. In hot versions of the dish, cayenne, red chili powder, or other spices give the typical red color.
Many regional varieties of flatbread, such as tandyr naan and afghan bread are baked in the tandoor.