The cytoskeleton is a cellular subsystem involved in various cellular
processes like division and locomotion. It consists of protein filaments
that interact with a number of proteins that control filament length and
generate stresses in the network. From a physical point of view, the
cytoskeleton is an active polar gel. Here, "active" indicates that the
system is permanently maintained out of thermodynamic equilibrium
such that physical descriptions of its dynamics require new tools
compared to the well-established statistical physics of equilibrium
systems. In the talk, examples of cytoskeletal dynamics will be
discussed, that highlight different approaches to physical descriptions
ranging from microscopic to phenomenological macroscopic theories.