A model is a representation of some part of the real world. There are two sorts of simple model; models of objects, and models of systems. An everyday example of a model which is an object is a portrait. An everyday example of a model of a system is weather forecasting, where changing weather data is gathered, and mathematics used to predict further changes. Models are fundamental to many aspects of life.
Building models involves mapping aspects of the world to a modelling context. For objects which are models, the object should look like the real object. For systems models, the model should have interactions which work like the world. Find out how.