This is a book about computer simulations of the EMC of electronic systems. EMC is concerned with the emission of electromagnetic disturbances and the immunity against them. Designing for EMC requires addressing multiple scales in geometry, signal amplitudes, and frequencies, making EMC simulation a challenging task. Despite these challenges, EMC simulation has become a success story. For many leading companies, it has evolved into an indispensable asset in their design processes. This book combines information about the domains that a simulation engineer should master, in order to successfully model and simulate EMC phenomena. In this chapter, we introduce the concept of modeling for EMC simulations. We give an overview of the simulation methodology and the simulation models presented throughout this book. We also discuss the reliability and the accuracy of EMC simulation models. Furthermore, we present the software package and the hardware used in the simulations.