This book invites the reader to look at the complex systems, such as living biological organisms and populations of species, among them, the human populations with special subsystems: a national economy, monetary system, a science etc, from the point of view of thermodynamics. To describe the complexity of such systems, one has to add a certain specific internal variables, which provoke revision of thermodynamic description, and in the first part of the book, the principles of thermodynamics of complex systems are formulated. The last chapter of this part discusses the statistical interpretation of thermodynamic relations. The subsequent chapters contains application of the principles to the description of dynamics of chemical reactions and complex fluids, growth and development of biological organism, dynamics of social structure and institutes.