The book gives the Liapunov background for the analysis and synthesis (design) of dynamic behaviour of general networks which represent a large class of nonlinear systems, predominantly physical, and in particular mechanical. It is meant to be a self-learning and thought provoking reference text. The introductory chapter refers to the basic concepts of static characteristics and dynamic processes. Subsequent chapters describe various formats of dynamic models and give a reference frame for their behaviour, introduce basic energy relations, fundamental to the dynamic use of the Liapunov method, and describe the method with implementations. The final chapter gives the methods of Liapunov design (synthesis) and control.