This book is about heuristics, popularly known as rules of thumb, educated guesses, intuitive judgments or simply common sense. In more precise terms, heuristics stand for strategies using readily accessible though loosely applicable information to control problem-solving processes in human beings and machine. This book presents an analysis of the nature and the power of typical heuristic methods, primarily those used in artificial intelligence (AI) and operations research (OR) to solve problems of search, reasoning, planning and optimization on digital machines.