Recent years have witnessed huge advances in computer technology and communication networks, entailing hard optimization problems in areas such as network design and routing. Metaheuristics are general high-level procedures that coordinate simple heuristics and rules to find good approximate solutions to computationally difficult combinatorial optimization problems. Among them, we find simulated annealing, tabu search, GRASP, VNS, genetic algorithms, and others. They are some of the most effective solution strategies for solving optimization problems in practice and have been applied to a very large variety of problems in telecommunications. In this chapter, we review the main components that are common to different metaheuristics. We also describe the main principles associated with several metaheuristic and we give templates for basic implementations of them. Finally, we present an account of some successful applications of metaheuristics to optimization problems in telecommunications.