Astronomy Colloquium

Over the past two decades, we have discovered and characterized the
lowest luminosity, most dark matter dominated, and least chemically
evolved galaxies known.  These ultra-faint Milky Way satellites have
provided new insight into the nature of dark matter and early
nucleosynthesis and chemical evolution.  With this era of discovery
poised to continue via Rubin, Roman, Euclid, and several spectroscopic
surveys, I will take stock of the current limits on our understanding
of ultra-faint dwarfs.  I will also present new results on their
binary star populations and the possible connection between
ultra-faint dwarfs and a largely ignored set of similarly faint but
more compact stellar systems.