There are reviewed conditions and mechanisms of the epileptic systems (ES) formation that are basis for pathogenesis of some forms of focal and generalized epilepsy in this work. It is shown the role of the determinant and dependent foci in the formation and elimination of ES using the example of simple ES in the form of multifocal epileptic complexes model. It is discussed the role of subcortical structures in the modulation of ES activity. There are experimentally justified diagnostic approaches of the determinant and dependent foci of ES, as well as the principles of the elimination of ES in this lecture. It is presented the data of the literature and the results of our own researches, showing that the basis for the development of epileptic activity during the different nature kindling is the formation of determinantal structures that cause the formation of ES. It is shown that stabilization of ES is the basis for the chronization of epilepsy and the pharmacoresistance development. The concept of an epileptic system as the basic pathophysiological mechanism of epilepsy is an approach to understanding its pathogenesis, creating models and developing new approaches to treatment.