The standard model of cosmology -- the ``Lambda cold dark matter'' model
-- is based on the idea that the dark matter is a collisionless
elementary particle, probably a supersymmetric particle. This model
(which mostly dates back to an early workshop in Santa Barbara in the
1980s) has been famously verified by observations of the cosmic
microwave background radiation and the large-scale distribution of
galaxies. However, the model has yet to be tested conclusively on the
small scales appropriate to most astronomical objects, such as galaxies
and clusters. I will review the current understanding of the
distribution of dark matter on small scales which derives largely from
large cosmological N-body simulations and I will discuss prospects for
detecting dark matter, either through its gravitational effect on
galaxies and clusters or, more directly, through gamma-ray annihilation
radiation.