  We review the physical properties of macromolecular networks, consisting of
semiflexible polymers such as actin. We start by giving a theoretical analysis
of the conformational statistics and mechanical response of single filaments.
Experimentally relevant quantities such as the end-to-end distribution function
and the force-extension relation are discussed. The results are used to analyze
the elastic modulus of an entangled solution of such objects. We also discuss
the short time and long time (terminal regime) dynamics and compare our results
with recent dynamic light scattering and viscoelastic measurements.
Furthermore, we analyze the elasticity transition in stochastic models of
crosslinked networks.
