In Entropy of Complex Processes and Systems , the author uses the notion of entropy for describing statistical properties of complex systems. This makes it possible to create a methodology for controlling and optimizing complex processes in practically all branches of industry involving any transformation of materials or substances. The author formalizes the understanding of many complex processes, including the development of the methodology of analytical computation of complex processes as applied in many industries such as ore processing or, more generally, in areas of natural sciences. The adequacy of the results of these calculations is confirmed by numerous experimental data obtained both on pilots and industrial facilities. The book also provides a thorough analysis of the underlying physical foundations of entropy performed from new standpoints that are of interest to theoreticians studying contemporary expositions of the general approach to extended thermodynamics.