A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model. Sometimes a clear distinction between the two terms is made, in which simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the simulation represents the evolution of the model over time. Another way to distinguish between the terms is to define simulation as experimentation with the help of a model. This definition includes time-independent simulations. Often, computers are used to execute the simulation.
Human-in-the-loop simulation of outer space
Motorcycle simulator of Bienal do Automóvel exhibition, in Belo Horizonte, Brazil
3DiTeams learner is percussing the patient's chest in virtual field hospital.
Car racing simulator
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Model of a molecule, with coloured balls representing different atoms
Part of the one-ninth scale model of Bourton-on-the-Water at Bourton-on-the-Water, Gloucestershire, England
Water-powered model of the UK economy – MONIAC in the Science Museum, London
Female model demonstrating brassiere for similarly-built potential buyers