A computer simulation or a computer model is a computer program that attempts to simulate an abstract model of a particular system.
Computer simulations have become a useful part of mathematical modelling of many natural systems in physics, chemistry and biology, human systems in economics, psychology, and social science and in the process of engineering new technology, to gain insight into the operation of those systems.
Traditionally, the formal modeling of systems has been via a mathematical model, which attempts to find analytical solutions to problems which enables the prediction of the behaviour of the system from a set of parameters and initial conditions.
Computer simulations build on, and are a useful adjunct to purely mathematical models in science, technology and entertainment.
The reliability and the trust people put in computer simulations depends on the validity of the simulation model.