Original: Weman, p 53 Gas tungsten arc welding (GTAW), or tungsten inert gas (TIG) welding (also sometimes erroneously referred to as heliarc welding), is a manual welding process that uses a nonconsumable tungsten electrode, an inert or semi-inert gas mixture, and a separate filler material.
Simplified: Gas tungsten arc welding (GTAW): GTAW is also known as TIG (tungsten inert gas welding).