Welding is a process of joining two or more metals together by melting them and using a filler material. It is a common technique used in metal fabrication and construction, and is often used to join pieces of metal that are too large or too thick to be joined by other methods. Welding is also used to repair damaged metal parts. The term 'WELD' comes from the Old English word 'welden, ' which means 'to join.'