This book chapter provides a comprehensive overview of additive friction stir (AFS), a promising manufacturing technique that utilizes the principles of additive manufacturing and friction stir welding. AFS represents an innovative approach to metal additive manufacturing that unwarps new possibilities for fabricating even complex metal parts or structures. AFS offers refined grain structure and enhanced mechanical properties making it ideal for complex and high-performance components. This chapter aims to serve as a valuable reference for basics and advancements in AFS technology and its broader industrial application.