  The nature of dark matter is one of the major puzzles of fundamental physics,
integral to the understanding of our universe across almost every epoch. The
search for dark matter takes place at different energy scales, and use data
ranging from particle colliders to astrophysical surveys. We focus here on
CMB-S4, a future ground-based Cosmic Microwave Background (CMB) experiment,
which is expected to provide exquisite measurements of the CMB temperature and
polarization anisotropies. These measurements (on their own and in combination
with other surveys) will allow for new means to shed light on the nature of
dark matter.
