  In the recent years neutrino experiments have studied in detail the
phenomenon of neutrino oscillations and most of the oscillation parameters have
been measured with a good accuracy. However, in spite of many interesting
ideas, the problem of flavor in the lepton sector remains an open issue. In
this review, we discuss the state of the art of models for neutrino masses and
mixings formulated in the context of flavor symmetries, with particular
emphasis on the role played by grand unified gauge groups.
