  We review the development in the field of lepton pair production since
proposing parton-antiparton annihilation as the mechanism of massive lepton
pair production. The basic physical picture of the Drell-Yan model has survived
the test of QCD, and the predictions from the QCD improved version have been
confirmed by the numerous experiments performed in the last three decades. The
model has provided an active theoretical arena for studying infrared and
collinear divergences in QCD. It is now so well understood theoretically that
it has become a powerful tool for new phyiscs information such as precision
measurements of the W mass and lepton and quark sizes.
