  Formation and disruption of dark-matter cusps are reviewed. Accumulation of
baryons at the center of a halo can displace the dark matter, converting
singular density cusps into low-density cores. The displaced mass can be of
order 10 M_b with M_b the mass of the infalling population. If M_b is
identified with the masses of the black holes currently observed at the centers
of bright galaxies, predicted core radii are ~a few hundred pc. Other
mechanisms, such as early mass outflow, may explain the large dark-matter cores
in dwarf and low-surface-brightness galaxies. Predictions of dark matter
annihilation radiation from the center of the Milky Way galaxy are shown to be
strongly dependent on the galaxy's merger history.
