  It is by now well established that galaxy evolution is driven by intrinsic
and environmental processes, both contributing to shape the observed properties
of galaxies. A number of early studies, both observational and theoretical,
have shown that the star formation activity of galaxies depends on their
environmental local density and also on galaxy hierarchy, i.e. centrals vs.
satellites. In fact, contrary to their central (most massive) galaxy of a
group/cluster, satellite galaxies are stripped of their gas and stars, and have
their star formation quenched by their environment. Large galaxy surveys like
SDSS now permit us to investigate in detail environment-driven transformation
processes by comparing centrals and satellites. In this paper I summarize what
we have so far learnt about environmental effects by analysing the observed
properties of local central and satellite galaxies in SDSS, as a function of
their stellar mass and the dark matter mass of their host group/cluster.
