SO(10) GUT Models and Their Present Success in Explaining Mass and Mixing Data

Some features of SO(10) GUT models are reviewed, and a number of such models in the literature are compared. While some have been eliminated by recent neutrino data, others are presently successful in explaining the quark and lepton mass and mixing data. A short description of one very predictive model is given which illustrates some of the features discussed. Future tests of the models are pointed out including one which contrasts sharply with those models based on an $L_e - L_{\mu} - L_{\tau}$ type symmetry.