Neutrino Oscillations will be discussed with the latest experimental results. The implication of these new findings will also be discussed. Namely, the first observation by Kamiokande that the number ratio of muon-neutrino and electron-neutrino in the atmosphere is not in accord with theoretical expectation has led to the non-zero masses of neutrinos and the neutrino oscillations among the three kinds of neutrinos. This finding has been verified later by Super-Kamiokande conclusively. Combined with results of other experiments like SNO, we now have the definite evidence that the solar neutrinos as emitted originally all as the electron-neutrinos oscillate on the way to become 1/3 electron-neutrinos, 1/3 muon-neutrinos and 1/3 tau-neutrinos to arrive to the earth detectors.
The non-zero masses of the neutrinos make them capable of total reflection at very low energies and this may in the future play essential role in the observation of the relic neutrinos which is supposed to tell us the state of our Universe at the time of 1 second after its birth.