People often refer to “models and simulations.” A model is a representation of something. The “something” can be an idea, a practice, a procedure, a physical location or a specific scenario. A model does not include every facet or detail but enough to represent the real article. A simulation is the manipulation of the model to understand a specific scenario. Here is an example of a simple simulation: You want to examine how to optimize a traffic intersection during rush hour. You draw a scale diagram representing the real intersection. This is the model. You put pieces representing cars on the map and move them in various patterns to see what might be the most efficient traffic flow. That is the simulation.