This introduction to the theory of feedback control systems covers the whole range of topics in control theory, unifying them in a single volume. Although the material is essentially mathematical, there is minimal emphasis on technicalities that are not absolutely essential for understanding control systems. Much of this second edition has been rewritten to take account of recent developments in control theory and how it is understood. A structural framework for the book is provided by three traditional topics in the applied mathematics of control theory: scalar, ordinary, and linear dynamic equations with constant coefficients; state space and optimal control theory in the form of dynamic programming; and elementary probability theory. Successful features have been retained from the first edition, including the uniform treatment of both continuous-time and discrete-time systems, the inclusion of a wide range of topics, and the provision of problems with answers, making it ideal in format for students and researchers in electrical and mechanical engineering, mathematical economics, mathematical biology, physiology, applied mathematics, and operational research.