  Neutrinoless double beta decay is a hypothetical radioactive process which,
if observed, would prove the neutrino to be a Majorana fermion: a particle that
is its own antiparticle. In this lecture mini-series I discuss the physics of
Majorana fermions and the connection between the nature of neutrino mass and
neutrinoless double beta decay. We review Dirac and Majorana spinors, discuss
methods of distinguishing between Majorana and Dirac fermions, and derive in
outline the connection between neutrino mass and double beta decay rates. We
conclude by briefly summarizing the experimental landscape and the challenges
associated with searches for this elusive process.
