MIG welding stands for Metal Inert Gas welding, which is a type of welding process that uses an electric arc to form between a consumable MIG wire electrode and the workpiece metal, heating the workpiece metal. The electrode is a metallic alloy wire, called a MIG wire, whose selection, alloy, and size are based primarily on the composition of the metal being welded, the process variation being used, joint design, and the material surface conditions. The wire is fed continuously from a spool mounted on a gun or inside the welding machine through a flexible tube and out of the nozzle on the welding gun or torch. The wire is fed continuously when the trigger on the welding gun is pulled, which also switches on the welding current and a shielding gas, and an electric arc forms. The shielding gas protects the weld pool from contamination, and the technical name for MIG welding is gas metal arc welding (GMAW). MIG welding is popular because it is an easy process to learn, and most people can become competent MIG welders by following some basic advice.