  Here, we provide an overview of theoretical approaches to semiflexible
polymers and their networks. Such semiflexible polymers have large bending
rigidities that can compete with the entropic tendency of a chain to crumple up
into a random coil. Many studies on semiflexible polymers and their assemblies
have been motivated by their importance in biology. Indeed, crosslinked
networks of semiflexible polymers form a major structural component of tissue
and living cells. Reconstituted networks of such biopolymers have emerged as a
new class of biological soft matter systems with remarkable material
properties, which have spurred many of the theoretical developments discussed
here. Starting from the mechanics and dynamics of individual semiflexible
polymers, we review the physics of semiflexible bundles, entangled solutions
and disordered cross-linked networks. Finally, we discuss recent developments
on marginally stable fibrous networks, which exhibit critical behavior similar
to other marginal systems such as jammed soft matter.
