TIG stands for "Tungsten Inert Gas welding".
Initially, TIG welding was known as Heliarc welding, named after the inert gas used in the process, helium.
Later, it was renamed Tungsten Inert Gas (TIG) welding because of the tungsten electrode used to create the arc.
The acronym GTAW stands for Gas Tungsten Arc Welding. The change in the acronym from TIG to GTAW reflects the technical terminology used in the welding industry.
GTAW more accurately describes the process because there are some blends of gas that contain active gas: for example a small addition of hydrogen is sometime added to argon for tig welding stainless steels and nickel alloys.
In addition there are gas blends like Stargon AL that contain very small amounts of active gases like nitrous oxide.
a gas (such as argon, helium, or special blend) is used to shield the tungsten electrode and weld puddle from atmospheric contamination, while the arc is created between the tungsten electrode and the workpiece.
So essentially, TIG welding and GTAW welding refer to the same welding process, but GTAW is the more precise and technical term used in the welding industry for welding procedures and other technical documents.
There are many different types of tungsten and the type of tungsten that is best for you depends on 2 main factors...
There are other factors but these are the main 2 in my opinion
Transformer tig welders AC frequency is fixed at either 50 or 60hz depending what part of the world you live.
A lot of folks who weld with older transformer style tig welders use 2% thor for DC and pure tungsten for AC.
Inverter tig welders usually have adjustable AC frequency that can go as high as 500hz. Some maybe higher.
I have used several different types of tungsten electrodes and the one best all around for both transformer tig welders as well as inverter tig welders is 2% lanthanated.
2% lanthanated is not necessarily the best tungsten for every single application but if I had to pick only one tungsten, it would be 2% lanth.
The I and G in TIG welding stands for "inert gas".
Argon is by far the most popular and most versatile shielding gas and might be all you ever need.
I like to mix a bit of helium or buy pre mixed argon/helium cylinders like 80/20 argon/helium for tig welding aluminum thicker than 1/8" but helium has become very expensive.
Another option for tig welding aluminum is a gas called Stargon AL.