  It has long been recognized that magnetic fields play an important role in
many astrophysical environments, yet the strength and structure of magnetic
fields beyond our solar system have been at best only qualitatively
constrained. The Galactic magnetic field in particular is crucial for modeling
the transport of Galactic CRs, for calculating the background to dark matter
and CMB-cosmology studies, and for determining the sources of UHECRs. This
report gives a brief overview of recent major advances in our understanding of
the Galactic magnetic field (GMF) and its lensing of Galactic and ultrahigh
energy cosmic rays.
