  We discuss the role coarse-grained models play in the investigation of the
structure and thermodynamics of bilayer membranes, and we place them in the
context of alternative approaches. Because they reduce the degrees of freedom
and employ simple and soft effective potentials, coarse-grained models can
provide rather direct insight into collective phenomena in membranes on large
time and length scales. We present a summary of recent progress in this rapidly
evolving field, and pay special attention to model development and
computational techniques. Applications of coarse-grained models to changes of
the membrane topology are illustrated with studies of membrane fusion utilizing
simulations and self-consistent field theory.
