Very important are computer models. These are representations of the original systems in a system of equations or data arrays on a computer. A good example is the drive of down-hill skier. This movement can be represented with a video, but in that way we cannot change no parameters of speed, angle etc. We cannot represent it as a symbolic model, because there is no system of equations, which is describing a concrete ski-run. But from the video we can take a digital (numerical) model and than start computer simulations. So computer simulations are experiments on numerical and symbolical models.

Computer simulations are widely recognized now as a new (third) method for the generation of new knowledge, beside theory building and experiment. But computer simulations are also used to make forecasts for the weather, forecasts for climate change or stock market developments. For thiese kind of simulatons special supercomputers are often used.