This document defines mathematical models and describes their construction and classification. A mathematical model is a description from a mathematical perspective of a real-world phenomenon, such as population size or physical phenomena like speed and density, with the goal of understanding the phenomenon and possibly predicting its future behavior. Mathematical models are classified according to the type of information used, representation type, determinism vs stochastic, and application/purpose. The construction of a mathematical model involves transforming the non-mathematical object into mathematical language, analyzing the mathematical model, and interpreting the mathematical analysis in relation to the original non-mathematical object.