The content of this book is divided into nine chapters. This short chapter is an introduction to the following chapters that discuss vari­ous subjects related to “Computational Welding Mechanics”. “Com­puter Simulation of Welding Processes” is the title of chapter two. The third chapter, “Thermal Analysis of Welds” provides the neces­sary background information for thermal stress fields, structure dis­tortion and deformation in order to enable those readers whose knowledge in these areas is limited, to understand the remainder of book. The heat supplied by the welding process produces complex thermal cycles in the weldment and these in turn cause changes in the microstructure of the heat affected zone, as well as the transient thermal stress. This results in the creation of residual stresses and distortions in the finished product. In order to analyze these prob­lems chapters four to six discuss analyzing the heat flow during welding, microstructure evolution and distortion analysis. Applica­tions of welding in industrial fields and the feasibility of real-time analysis will be presented in chapters seven. Cracks may occur in the weld metal or in the heat affected zone. Chapter eight discusses the fracture of the weldment. The authors’ preferred input data for a Computational Weld Mechanics analysis are described in chapter nine.