Coke is a fuel used mainly in blast furnaces to reduce iron oxide to produce iron. It contains carbon, and is similar to coal. It is made from coal by cooking out things that are not carbon. Coke is a product of destructive distillation of coal. This is done in an airless furnace or oven (kiln) at temperatures as high as but usually around . This baking drives off volatile parts of the coal, such as water, gas, and tar.