This is the most complex form of welding, and one that can consume you when you graduate to it. It is very quiet because the electrode is not being consumed. You manually hold the tungsten electrode over the weld area, which is shielded by an inert or semi-inert gas mixture to protect the area. As you heat the area up, you manually fill the joint with a hand-fed wire. You need to melt the material just enough, so that you can fill it just enough. Think of it as a micro-super-hot heat source that is melting the metal. This allows for welding very thin or thick material, great control, and an incredible looking weld, but it is very slow, and if you suck it looks horrible. The thickness of what you can weld is based on the output of the machine and the thickness of the filler metal. TIG units are not available at your big-box stores.