  Dark matter has been introduced to explain many independent gravitational
effects at different astronomical scales, in galaxies, groups of galaxies,
clusters, superclusters and even across the full horizon. This review describes
the accumulated astronomical, astrophysical, and cosmological evidence for dark
matter. It is written at a non-specialist level and intended for an audience
with little or only partial knowledge of astrophysics or cosmology.

Cosmology and Nongalactic Astrophysics