This book provides some fundamental information about simulation and specifically Discrete-event simulation and it tries to introduce DES application in industrial companies. Furthermore, it addresses some challenges of its application plus some suggestions for handling them by mentioning a real-life problem in production. Finally, it provides a framework plus a standard work method for effective and efficient use of Discrete Event Simulation for production development purposes. The target group can vary from high ranked managers deciding about the use of simulation in their organizations to the production managers who consider the application of simulation for their daily problems. It is also useful for students who are involved in Discrete-event simulation project and all those who are interested in Discrete Event Simulation in general.