The book contains the theory of linear and non-linear automatic control systems, including methods of mathematical description, methods for studying stability, quality, correction and synthesis of systems. Specific issues of the theory of discrete systems and the theory of optimal control systems are especially considered. The last part of the book outlines the principles of building adaptive systems. Appendices to the book contain a number of nomograms, tables and formulas useful in practical calculations of automatic control systems. The book is intended for students of universities of electrical and power engineering specialties.