Charcoal is one of the oldest forms of fuel that we are using for centuries. It's made from wood and is obtained by heating wood to extreme temperatures. If we see the ancient technology, it was made by building a fire in a pit, then submerging it into the mud. It results in partial combustion, where water and impurities get removed, and we get the pure carbon. In simple terms, charcoal is nothing but half-burnt wood.