This final volume of the Course of Theoretical Physics deals with physical kinetics, in the wide sense of the microscopic theory of processes in systems not in statistical equilibrium. In contrast to the properties of systems that are in statistical equilibrium, the kinetic properties are much more closely related to the nature of the microscopic interactions in a particular physical object. This is the reason for the enormous variety in such properties and the considerably greater complexity of the relevant theory. The choice of topics to be included in a general course of theoretical physics thereby becomes less clear.