GTAW stands for gas tungsten arc welding, also known as TIG (tungsten inert gas welding).
In this welding process, the welder must use both hands at the same time – one hand to hold the welding torch in and another hand to hold the filler metal. Coordination is required but the welder enjoys more control over the finished product.
If you were learning to drive a car, GTAW would be like driving a stick shift.