  Tidal debris streams from galaxy satellites can provide insight into the dark
matter distribution in halos. This is because we have more information about
stars in a debris structure than about a purely random population of stars: we
know that in the past they were all bound to the same dwarf galaxy; and we know
that they form a dynamically cold population moving on similar orbits. They
also probe a different region of the matter distribution in a galaxy than many
other methods of mass determination, as their orbits take them far beyond the
typical extent of those for the bulk of stars. Although conclusive results from
this information have yet to be obtained, significant progress has been made in
developing the methodologies for determining both the global mass distribution
of the Milky Way's dark matter halo and the amount of dark matter substructure
within it. Methods for measuring the halo shape are divided into "predictive
methods," which predict the tidal debris properties from the progenitor
satellite's mass and orbit, given an assumed parent galaxy mass distribution;
and "fundamental methods," which exploit properties fundamental to the nature
of tidal debris as global potential constraints. Methods for quantifying the
prevalence of dark matter subhalos within halos through the analysis of the
gaps left in tidal streams after these substructures pass through them are
reviewed.
