Description
The phenomenology of 3-neutrino mixing, the present status of our knowledge about the 3-neutrino mixing parameters, including the absolute neutrino mass scale, and of the Dirac and Majorana CP violation in the lepton sector, are summarised. The current theoretical ideas about the origins i) of neutrino masses and of the enormous disparity between their values and the values of the charged lepton and quark masses, and ii) of the pattern of neutrino mixing revealed by the neutrino oscillation experiments, are reviewed, with the non-Abelian discrete symmetry approach considered in somewhat greater detail. The possibilities to test these idea are also briefly discussed.
