The purpose of this book is to present the main metaheuristicsand approximate and stochastic methods for optimization of complexsystems in Engineering Sciences. It has been written within theframework of the European Union project ERRIC (Empowering RomanianResearch on Intelligent Information Technologies), which is fundedby the EU’s FP7 Research Potential program and has beendeveloped in co-operation between French and Romanian teachingresearchers. Through the principles of various proposed algorithms(with additional references) this book allows the reader to explorevarious methods of implementation such as metaheuristics, localsearch and populationbased methods. It examines multi-objective andstochastic optimization, as well as methods and tools forcomputer-aided decision-making and simulation fordecision-making.