Computer simulation is the running of a mathematical model on a computer,
the model being designed to represent the behaviour of, or the outcome of, a
real-world or physical system. The reliability of some mathematical models can
be determined by comparing their results to the real-world outcomes they aim
to predict. Computer simulations have become a useful tool for the
mathematical modeling of many natural systems in physics (computational
physics), astrophysics, climatology, chemistry, biology and manufacturing, as
well as human systems in economics, psychology, social science, health care
and engineering. Simulation of a system is represented as the running of the
system's model.