Modeling is something that all human beings do. Children create models out of playdough, tinker toys, legos, blocks, cards, sand, and the like. Engineers create clay models of automobiles, metal models of aircraft, wooden models of bridges, plastic models of cities, hand-drawn models of buildings, and computer models of most of the things they create. Natural scientists create physical models of molecules, the human body, and the solar system, and mathematical and/or written models of the evolution of the universe. Social scientists create computer and written models of the mind, mathematical and computer models of the economy, and physical models of ancient civilizations. Managers build financial models with spreadsheet programs and database applications. Playwrights create models capturing aspects of the human condition.

Humans create models for a variety of reasons. Models are simplifications of reality and (usually) help people to clarify their thinking and improve their understanding of the world. Models can be used for experimentation. A computer model, for instance, can compress time and space and allow many system changes to be tested in a fraction of the time it would take to test them in the real world. Further, testing changes on a model, rather than on an actual system, is a good way to avoid "shooting yourself in the foot." That is, if a change does not perform well in a model of a system, it is questionable as to whether it will perform well in the actual system itself. In addition, experimenting on a model can avoid causing harm to an actual system, even when the change being tested is successful. For example, testing a more effective sprinkler system design does not require setting an actual building on fire, if the testing is done on a model of the building.