Modern polymer materials are designed by applying principles of correlation between chemical structure, physical macrostructure and technological properties. Fundamentals of polymer physics are explained in this book without excessive use of calculations. Four main sections treat relaxation of polymers, melting and crystallization, the mechanism of deformation in thermoplastics, elastomers and multiphase systems, and thermodynamics of mixing and swelling of polymers and polymer networks. The book presents the theoretical models of polymer physics in a comprehensive style and relates their applicability to real polymer systems in terms of the available experimental observations.