  While galaxies move through the intracluster medium of their host cluster,
they experience a ram pressure which removes at least a significant part of
their interstellar medium. This ram pressure stripping appears to be especially
important for spiral galaxies: this scenario is a good candidate to explain the
differences observed between cluster spirals in the nearby universe and their
field counterparts. Thus, ram pressure stripping of disk galaxies in clusters
has been studied intensively during the last decade. I review advances made in
this area, concentrating on theoretical work, but continuously comparing to
observations.
