In order to understand properties, functions and the behavior of matter, objects, devices or even living organisms, models play an important role in physics disciplines. Modelling can be done on very different levels and sometimes even coalesce with physics theories. Since so far there is no “Theory of Everything” which describes nature at all conditions and length scales, several theories (e.g. classical mechanics, quantum mechanics, relativity) have been established for selected conditions. An overview and examples will be presented how theories and models in physics provide a framework for understanding and describing our world.