Modellers frequently classify their model as being one type or another: “differential equation model”, “matrix model”, “individual-based model”, and so on. Simile is capable of handling most of these model types — sometimes directly, sometimes with some recasting. The aim of this section is to consider some of the more common model types, and how they are handled in Simile. It should be remembered, however, that a model in Simile can combine what would normally be considered distinct and non-combinable modelling approaches. Thus, in Simile, it is quite possible to have a model that combines, for example, differential-equation, matrix, and individual-based modelling.