I searched and found that nobody has really asked about welding before. So i have a few questions for the experienced.

What is the difference between a mig and tig welder?

Is there a welder that is more flexible in use than another?

Im trying to find out what would be good to do exhuast work, fender sheet metal work, and possible frame fabrication for air bags. Is there something out there that can do all of that, or two different types. Im looking for something cheep too, not junk but nowhere near top of the line either. Thanks