Coal is an organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. Coal is a combustible rock and along with oil and natural gas it is one of the three most important fossil fuels. Coal has a wide range of uses; the most important use is for the generation of electricity.
Coke is produced by heating coal under controlled conditions in the absence of air. This drives off some of the volatile materials and concentrates the carbon content. Coke is then used as a high carbon fuel for metal processing and other uses where an especially hot-burning flame is needed.