  The paper is devoted to recent advances in stochastic modeling of anomalous
kinetic processes observed in dielectric materials which are prominent examples
of disordered (complex) systems. Theoretical studies of dynamical properties of
those "structures with variations" [Goldenfield and Kadanoff 1999 Science 284
87--9] require application of such mathematical tools by means of which their
random nature can be analyzed and, independently of the details differing
various systems (dipolar materials, glasses, semiconductors, liquid crystals,
polymers, etc.), the empirical universal kinetic patterns can be derived. We
begin with a brief survey of the historical background of the dielectric
relaxation study. After a short outline of the theoretical ideas providing the
random tools applicable to modeling of relaxation phenomena, we present
probabilistic implications for the study of the relaxation-rate distribution
models. In the framework of the probability distribution of relaxation rates we
consider description of complex systems, in which relaxing entities form random
clusters interacting with each other and single entities. Then we focus on
stochastic mechanisms of the relaxation phenomenon. We discuss the diffusion
approach and its usefulness for understanding of anomalous dynamics of the
relaxing systems. We also discuss extensions of the diffusive approach to the
systems under tempered random processes. Useful relationships among different
stochastic approaches to the anomalous dynamics of complex systems allow us to
get a fresh look on this subject. The paper closes with a final discussion on
achievements of stochastic tools describing the anomalous time evolution of the
complex systems.
