  The non-linear process of cosmic structure formation produces gravitationally
bound overdensities of dark matter known as halos. The abundances, density
profiles, ellipticities, and spins of these halos can be tied to the underlying
fundamental particle physics that governs dark matter at microscopic scales.
Thus, macroscopic measurements of dark matter halos offer a unique opportunity
to determine the underlying properties of dark matter across the vast landscape
of dark matter theories. This white paper summarizes the ongoing rapid
development of theoretical and experimental methods, as well as new
opportunities, to use dark matter halo measurements as a pillar of dark matter
physics.
