  The nature of dark matter is one of the outstanding questions of
astrophysics. The internal motions of member stars reveal that the lowest
luminosity galaxies in the Local Group are the most dark-matter dominated. New
large datasets allow one to go further, and determine systematic properties of
their dark matter haloes. We summarise recent results, emphasising the critical
role of the dwarf spheroidal galaxies in understanding both dark matter and
baryonic processes that shape galaxy evolution.
