A computer simulation, a computer model or a computational model is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system in computational physics, chemistry and biology, psychology, and social science and in the process of engineering new technology. We do this to gain insight into the operation of those systems, or to observe their behavior. To learn about the system we must first build a model of some sort and then operate the model. The use of simulation is an activity that is as natural as a child who role plays. To understand reality and all of its complexity, we must build artificial objects and dynamically act out roles with them.