Soft matter is a concept which covers polymers, liquid crystals, colloids, amphiphilic molecules, glasses, granular and biological materials. One of the fundamental characteristic features of soft matter is that it exhibits various mesoscopic structures originating from a large number of internal degrees of freedom of each molecule. Due to such intermediate structures, soft matter can easily be brought into non-equilibrium states and cause non-linear responses by imposing external fields such as an electric field, a mechanical stress or a shear flow. Volume 4 of the series in Soft Condensed Matter focuses on the non-linear and non-equilibrium properties of soft matter. It contains a collection of review articles on the current topics of non-equilibrium soft matter physics written by leading experts in the field. The topics dealt with in this volume includes rheology of polymers and liquid crystals, dynamical properties of Langmuir monolayers at the air/water interface, hydrodynamics of membranes and twisted filaments as well as dynamics of deformable self-propelled particles and migration of biological cells. This book serves both as an introduction to students as well as a useful reference to researchers.