Neutrino physics 2003—status and perspectives

The current status of neutrino physics is reviewed. With the recent establishment of non-zero neutrino masses and lepton flavour mixing a long-standing open issue has been resolved. However, fundamental questions still remain unanswered, among them the absolute neutrino mass scale, precise values for the mixing angles and CP-phase, and the questions whether the neutrino is its own antiparticle and whether sterile neutrinos do exist in nature. The article describes ideas and plans to tackle these issues in future experiments, and comments on the increasingly important role of neutrinos as messengers for the investigation of astrophysical processes.