  The decay of the free neutron into a proton, electron, and antineutrino is
the prototype semileptonic weak decay and the simplest example of nuclear beta
decay. The nucleon vector and axial vector weak coupling constants G_V and G_A
determine the neutron lifetime as well as the strengths of weak interaction
processes involving free neutrons and protons that are important in
astrophysics, cosmology, solar physics and neutrino detection. In combination
with a neutron decay angular correlation measurement, the neutron lifetime can
be used to determine the first element of the CKM matrix Vud. Unfortunately the
two main experimental methods for measuring the neutron lifetime currently
disagree by almost 4 sigma. I will present a brief review of the status of the
neutron lifetime and prospects for the future.
