Providing an overview of a variety of topics, this book looks at the classification of various welding processes; the modeling aspects of GMAW; physics of welding; metal transfer characteristics; weld pool geometry; process voltages and variables; power supplies; sensing (sensors for arc length, weld penetration control, weld pool geometry, using optical and intelligent sensors); control techniques of PI, PID, multivariable control, adaptive control, and intelligent control. Finally, the book illustrates a case study presented by the authors and their students at Idaho State University, in collaboration with researchers at the Idaho National Engineering and Environment Laboratory.