Computer Numerical Control (CNC) controllers, working as a brain for manufacturing automation, are high value-added products counting for over 30% of the price of machine tools. CNC technology is generally considered as a measure for the level of manufacturing technology of a nation. Often referred to as "The Flower of Industrial Technology", the development of CNC technology depends upon the integration of technologies from computer, hardware, machining, and other industries, and requires strategic long-term support, mostly on a governmental level. Theory and Design of CNC Systems covers the elements of control, the design of control systems, and modern open-architecture control systems. Topics covered include Numerical Control Kernel (NCK) design of CNC, Programmable Logic Control (PLC), and the Man-Machine Interface (MMI), as well as the major modules for the development of conversational programming methods. The concepts and primary elements of STEP-NC are also introduced. A collaboration of several authors with considerable experience in CNC development, education, and research, Theory and Design of CNC Systems is a highly focused textbook on the principles and development technologies of CNC controllers, which can also be used as a guide for those working on CNC development in industry.