Abstract: The origin of fermion masses and mixing remains a puzzle in particle physics. I will describe how the number of parameters that parametrize all fermion masses and mixing angles can be reduced by imposing symmetries, and argue why small neutrino masses and large leptonic mixing are closely connected to the unification of the strong, weak and electromagnetic forces. This is demonstrated in a specific model based on supersymmetric SO(10) combined with an SU(2) family symmetry, in which a set of symmetric matrices with twelve parameters leads to values of twenty-two measurable masses and mixing angles of quarks and leptons; the available experimental data is in agreement for atmospheric and solar neutrinos, leaving the predicted masses of neutrinos and some lepton mixing angles to be verified by future experiments. The predictions for the branching fractions of the lepton flavor violating charged lepton decays in this model are accessible to the next generation of experiments. Current status of the theoretical predictions for proton decay will also be reviewed. Finally, I will delineate a possible connection between neutrino oscillations and the baryon asymmetry of the Universe.