MIG or MAG welding (the only difference is the gas that is used as a shielding gas) is a welding process that was developed after the Second World War that has grown in practice year after year.
MIG/MAG welding is a constant voltage process where a shield gas is used to protect the welding from contaminants. The fact that it is a constant voltage process guarantees increased productivity, while the continuous gas prevents slag. MIG welding is easier, more practical, and faster than TIG, and is used when productivity and simplicity are important. The elevated current density (100-250 A/mm²) allows for an increased deposition rate.