  This article reviews the current theoretical and experimental status of the
field of muon decay and its potential to search for new physics beyond the
Standard Model. The importance of rare muon processes with lepton flavor
violation is highly stressed, together with precision measurements of normal
muon decay. Recent up-to-date motivations of lepton flavor violation based on
supersymmetric models, in particular supersymmetric grand unified theories, are
described along with other theoretical models. Future prospects of experiments
and muon sources of high intensity for further progress in this field are also
discussed.
