The book in a popular form tells about the main patterns and anomalies observed in the study of the rheological properties of polymers for the most important cases of their use. In it, without a complex mathematical apparatus, the physicochemical foundations of deformation in melts, solid polymers, dispersions and solutions are considered. Numerous examples of practice are given when knowledge of the rheological characteristics of the behavior of these systems is decisive for their correct use. The book is of interest to a wide range of engineering, technical and scientific workers involved in the processing and use of polymer materials. It can also be used by students of relevant universities.