  A coarse-grained simulation model eliminates microscopic degrees of freedom
and represents a polymer by a simplified structure. A priori, two classes of
coarse-grained models may be distinguished: those which are designed for a
specific polymer and reflect the underlying atomistic details to some extent,
and those which retain only the most basic features of a polymer chain (chain
connectivity, short-range excluded-volume interactions, etc.).
  In this review we mainly focus on the second class of generic polymer models,
while the first class of specific coarse-grained models is only touched upon
briefly.
