Neutrinoless double-beta decay and neutrino physics

The connection of neutrino physics with the neutrinoless double-beta decay is reviewed. After presenting the current status of the Pontecorvo-Maki-Nakagawa-Sakata matrix and the theoretical background of neutrino mass and lepton mixing, we will summarize the various implications of neutrino physics for the double-beta decay. The influence of light sterile neutrinos and other exotic modifications of the three neutrino picture is also discussed.