Welding is a fabrication process that joins materials usually metals by using high heat to melt the parts together and allowing them to cool causing fusing. Many different energy sources can be used for welding including gas flame, electric arc, a laser and electron beam, friction and ultrasonic. This book includes various methods of welding and design of weld joints, weldability and testing of weldments. Welding technology also includes latest and newer techniques for welding. Our hope is that this book, through its careful explanations of concepts and its use of numerous examples, sketches and figures, bridges the gap between knowledge and proper application of that knowledge.