This textbook provides fundamental understanding on technological aspects related to arc welding, heat flow, relevant metallurgical transformations, and quality assurance methodologies joints. It has been composed keeping in purview the requirements of those interested in research and development in the field of metal joining. The contents focus on the fundamentals of physics of welded joints, arc welding processes, brazing and soldering, heat flow in welding, welding metallurgy, design of welded joints, and inspection and testing of welded joints and weldability of metals. This book will be useful to both academics and those in the industry.