A model can be defined as an abstraction of reality which accounts for those properties of a phenomenon that are pertinent to the purpose of the model. Models are used in anesthesia to understand the various physiologic, pharmacological and physical processes that occur during anesthesia. Indeed, many different types of models that comply with our definition can be distinguished. Early models consisted of electrical models of the arterial blood dynamics and cardiovascular system. Physical models of drug uptake and distribution have been developed to explain the kinetics of volatile anesthetics in the body. The goal of this paper is to introduce the reader to some of the types of models that been used to facilitate education and research in anesthesia. These examples will elucidate the steps involved in developing a model and the various types of models that have proven useful.