This document discusses simulation modeling and its applications. It begins with definitions of simulation as operating a model of a system over time to study its behavior. Simulation is used to evaluate system performance under different configurations before implementation. The key advantages are exploring "what if" scenarios without disrupting real systems and testing new designs. Common applications include manufacturing, construction, military, logistics and transportation. The document outlines the steps in a simulation study and discusses when simulation is appropriate versus not. It concludes with references on modeling and simulation.