Metal inert gas welding is a welding process that uses a wire electrode that is fed through a welding gun and is melted off continuously in an electric arc. An inert shielding gas is produced by the welding gun to protect the arc from contamination.
The shielding gas in MIG welding is typically argon. The argon is sometimes mixed with oxygen, carbon dioxide or helium, depending on the materials being welded. MIG welding produces a uniform weld bead and requires little cleanup. It is popular because it is fairly easy to learn, has high productivity, can be utilized in all positions and is mechanized easily.