Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool causing fusion. Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal
Gas welding is rarely used anymore and has been largely superseded by TIG welding. Gas welding kits require oxygen and acetylene and are very portable. They are still sometimes used to weld bits of car exhaust back together.