Classification of arc-based deposition is given. The arc created between two electrodes is used as a heat source in metal welding, which is applied in AM. The processes are based on gas tungsten arc welding, plasma welding (plasma non-transferred arc, plasma transferred arc), and gas metal arc welding. The plasma is less intense and collimated than other beams, such as electron beam or laser. But the plasma beam can still be used to distinguish it from other non-plasma beam arc-based heat sources.