This book presents the DG/K-based method of surface generation, a novel and practical mathematical method for designing gear cutting tools with optimal parameters. The author, an industry leader for the past 30 years, proposes a scientific classification for all possible kinds of the gear machining meshes before discussing optimal designs of gear cutting tools. This classification makes it possible to consider all possible designs of gear cutting tools, including those currently used in practice and those expected to be used in the future. It also allows the author to develop scientific predictions and optimal designs. In most cases, solutions appear in analytical form and/or graphical form.