A model is a simplified representation or abstraction of a complex system or phenomenon, used to understand, predict, or explain aspects of that system or phenomenon. Models can take many different forms, including mathematical equations, physical replicas, computer simulations, or conceptual frameworks.

In the context of physics, models can be particularly useful for understanding systems that are too complex or difficult to observe directly. For example, in relativity and quantum mechanics, the behavior of particles and waves can be very different from what we observe in everyday life, and it can be challenging to develop a clear intuitive understanding of these phenomena. Models can provide a simplified framework that allows physicists to explore the behavior of these systems, make predictions about their behavior, and test those predictions against experimental observations.