The book deals with the most accurate method to describe thermodynamic property data, with empirical multiparameter equations of state. Due to new theoretical approaches, to increasing demands on the accuracy of thermodynamic property data, and to increasing computer power such equations became a valuable tool for every day calculations in scientific and engineering applications, rather than just the basis of printed property charts and tables. The book is dedicated both to users, who apply such formulations either in form of commercially available software or in form of programs written by themselves, and to scientists engaged in the development of empirical equations of state. Starting from a brief history, it covers the fundamentals of this subject as well as the most recent developments in the fields of highly accurate reference equations, of equations for advanced technical applications, and of the description of mixtures with multiparameter equations of state.