In this introductory chapter, mathematical modelling and the process of mathematical modelling are introduced and described in detail. Three of the more commonly used approaches of mathematical modelling – namely, the empirical, deterministic and simulation modelling approaches – are discussed. For each approach, a simple example is used to illustrate the key ideas in the approach. The chapter also includes a discussion on the skills and competencies required of a student who wishes to learn or embark on a mathematical modelling activity. Some features of an electronic spreadsheet, such as Microsoft Excel, that can be applied in mathematical modelling are described in detail and examples showing how they may be used in mathematical modelling are presented.