  According to the current paradigm, galaxies form and reside in extended cold
dark matter (CDM) halos and in turn are key tracers of cosmological structure.
Understanding how different types of galaxies occupy halos of different masses
is one of the major challenges facing extragalactic astrophysics. The observed
galaxy properties depend on the environment surrounding the galaxy. Within the
framework of most galaxy formation models the environmental dependence of the
galaxy population is mainly due to the change of the halo mass function with
large-scale environment. Such models make precise predictions for how galaxy
clustering should depend on environment. We will illustrate this by presenting
analytical models of dark matter and galaxy clustering along with results
obtained from numerical simulations. With these results we can hope to obtain a
better understanding of the link between galaxies and dark matter and thereby
constrain galaxy formation models.
