Char's the solid material that remains after light gases (for example coal gas) and tar (for example coal tar) have been driven-out or released from a carbonaceous material, during the initial stage of combustion, which's known as carbonization, charring, devolatilization or pyrolysis. Further stages of efficient combustion (with or without char deposits) are known as gasification reactions, ending quickly when the reversible gas phase water gas shift reaction reaches equilibrium.… (More on Char)