Neutrino physics: A theoretical review

I briefly review the status of neutrino physics from a theoretical point of view. After giving updated results from a global fit to neutrino oscillation data I discuss the most important open questions in neutrino phenomenology. I highlight the puzzeling observations that neutrinos are so much lighter than all other fermions and that flavour mixing is very different in the lepton and quark sectors. I present a few approaches on how to extend the Standard Model in order to give mass to neutrinos including highand low-scale seesaw mechanisms. The discussion is highly biased and does not aim of being complete.