It is a lightweight black carbon residue produced by removing water and other volatile constituents from animal and plant materials. It is usually produced by slow pyrolysis — the heating of wood or other organic materials in the absence of oxygen. This process is called charcoal burning.

It is an impure form of graphic carbon, obtained as a residue when carbonaceous material is partially burned, or heated with limited access of air. Coke, carbon black, and soot may be regarded as forms of charcoal; other forms often are designated by the name of the materials, such as wood, blood, bone, and so on, from which they are derived. It has been replaced by coke for reducing metal ores in blast furnaces and by natural gas as a source of carbon in making certain chemicals, but it is still employed in making black gunpowder and in case-hardening metals. 
Formerly, charcoal production from wood was an important source of acetone, methyl alcohol, and acetic acid, all of which are now produced from other raw materials.