At its simplest, an earth oven is a pit in the ground used to trap heat and bake, smoke, or steam food.
Earth ovens have been used in many places and cultures in the past, and the presence of such cooking pits is a key sign of human settlement often sought by archaeologists.
Broadly speaking, ovens have always been used either for cooking, prominently for baking; or for industrial purposes – for producing metals out of ores, charcoal, coke, ceramic, etc.
Industrial ovens can be used for large or small volume applications, in batches or continuously with a conveyor line, and a variety of temperature ranges, sizes and configurations.
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes.