  Neutrinos have no electric charge, but a magnetic field can indirectly affect
neutrino properties and interactions through its effect on charged particles.
After a brief field-theoretic discussion of charged particles in magnetic
fields, we discuss two broad kinds of magnetic field effects on neutrinos.
First, effects which come through virtual charged particles and alter neutrino
properties. Second, effects which alter neutrino interactions through charged
particles in the initial or final state. We end with some discussion about
possible physical implications of these effects.
