  A review of the problem of neutrino mass, mixing and oscillations is given.
Possible phenomenological schemes of neutrino mixing are discussed. The most
important consequences of neutrino mixing--neutrino oscillations are considered
in some details. The data of atmospheric, solar and LSND experiments are
discussed. The results of phenomenological analyses of the data under the
assumption of the mixing of three and four massive neutrinos are shortly
presented.
