Coke is a gray, hard, porous coal-based fuel with a high carbon content and few impurities made by heating coal or oil in the absence of air -- a destructive distillation process. It is an important industrial product, mainly used in iron ore smelting, but also as a fuel in furnaces and forges when air pollution is a concern.

The off-spec term "coke" generally refers to a product extracted from low-ash and low-sulfur bituminous coal through a process called coking. A similar product called petroleum prices for coke or petroleum prices for coke is extracted from crude oil in refineries. Coke can also form naturally through geological processes.
Many historical sources dating back to the 4th century describe coke production in ancient China. [2] The Chinese first used coke for heating and cooking no later than the 9th century. [citation needed] By the first few decades of the 11th century, Chinese blacksmiths in the Yellow River valley began fueling their furnaces with prices for coke, solving their fuel problems in tree-sparse regions[3]

China is the largest prices for coke producer and exporter today. [4] China produces 60% of the world's coke. Concerns about air pollution have driven technological change in the prices for coke industry, eliminating obsolete coking technologies that are not energy efficient.