ABSTRACT
Model is an everyday word. Look it up in the dictionary and you are likely to find upwards of eight definitions as a noun and four or more as a verb. Meanings range from making things out of clay to using mathematics to someone who struts down the catwalk. Leaving aside this last category, most of the definitions have one thing in common: simplification or reduction in complexity. At its easiest, a model is a simplification of reality in terms that we can easily understand. As illustrated in Figure 4.1, a map can be viewed as a model.
