Robot welding is most commonly associated with MIG (Metal Inert Gas) welding or resistance spot welding. However, other methods of robot welding are frequent used, including TIG (Tungsten Inert Gas), Plasma, TIG Filler (TIG Welding with Filler Rod) and Laser Welding. It is estimated that the world wide population of operational industrial robots now exceeds 1,000,000 robots, with over half of that number being used for robot welding.