Microscopic models describe traffic flow dynamics in terms of single vehicles. The mathematical formulations include car-following models, the topic of this and the next two chapters, and cellular automata, which are described in Chap. 14 . This chapter begins with a discussion of general principles that apply to all microscopic models of traffic flow, such as the microscopic steady-state equilibrium, the micro-macro transition to the fundamental diagram, and heterogeneous traffic. The next sections discuss Newell’s car-following model and the Optimal Velocity Model (and variants thereof) as the generic examples of simple car-following models. The last section presents the linear control model which is used as simplified basis for many ACC high-level controllers.