There is no shortage of books on polymer physics. Many of them very good. In writing yet another one, the prospective author should thus have a firm vision why his or her book would be picked up by the prospective reader when compared to all the other ones available on the market. This particular book, that grew out of a series of lectures for graduate students given by Prof. Toshihiro Kawakatsu at several universities in Japan, was conceived as an introduction to the concepts as well as theoretical methods used in contemporary research in the physics of polymers and complex fluids. It is built around simple but essential examples of mesoscale behavior of polymers taken from various areas of polymer physics that illustrate these concepts as well as advanced statistical mechanical methods used in polymer science.