Controllers are designed to make certain physical variables of a system behave in a desired way by manipulating some input variables. Simple low-order controllers are usually preferred to better performing but high-order controllers, because of their simplicity and practicality. In this book, the problem of parameterizing stabilizing fixed low-order controllers for linear time-invariant single-input single-output systems is studied. Using a generalization of the Hermite-Biehler theorem, an algorithm is given for the determination of stabilizing gains for linear time-invariant systems. By applying this stabilization algorithm to three subsidiary plants, the set of all stabilizing first-order controllers of any given plant are determined. The method given is applicable to both continuous and discrete time systems and can accommodate various further realistic design constraints. This book can be used to complement and enrich the contents of any graduate course on feedback control systems. The fixed order controller algorithms provided will be of interest to every control system engineer and theorist.