This book presents wire arc additive manufacturing (WAAM), its variants, processing steps, and the mechanical and microstructural aspects of developed components, along with a logical sequence that provides a ready reference. Wire Arc Additive Manufacturing: Fundamental Sciences and Advances introduces the timeline and history of WAAM. It offers a critical review of WAAM, its variants, processing steps, and the mechanical and microstructural aspects of developed components. The book showcases the methods and practices that need to be followed to synchronise WAAM with other conventional metal additive manufacturing, as well as other conventional techniques. The process steps, equipment, and the different materials used are discussed in detail, along with the various process parameters and their optimisation to counter the challenges and defects. Applications, trends, and case studies are also included in the book. This book, aimed at providing a concrete reference for researchers, academics, and professionals, allows for a thorough understanding of the different concepts and intricacies of WAAM.