A Review on Neutrino Physics, Mass and Oscillations

We present a short review of the present status of the problem of neutrino masses and mixing including a survey of theoretical motivations and models, experimental searches and implications of recently appeared solar and atmospheric neutrino data, which strongly indicate nonzero neutrino masses. Such data apparently requires the existence of light sterile neutrino in addition to the three active ones and two-generation nearly maximal mixing.