A simulation is an activity that imitates a real situation or process, usually to save money and build experience in a safe, virtual and risk-free environment. Simulations can be live activities, computer-based activities or a combination of both.
For example, a batting cage, a driving range, and a flight simulator are all forms of simulation, places where mistakes are far less costly and can even be encouraged. Simulations as training tools have been used successfully in diverse industries (medicine, nuclear power, aviation, military) for many years when mistakes in the real world are unacceptable.
High-fidelity simulations replicate the skills to be taught on the same kind equipment that the student will work on. Low-fidelity simulations replicate the concepts to be taught, but not in the environment where students actually use the concepts.
One-hour recorded Webcast: "Driving Insight Through Process Modeling" - http://www.moresteam.com/presentations/webcast-process-modeling.cfm