It has been 3 years since a first evidence for the existence of high-energy astrophysical neutrinos was announced by the IceCube Collaboration (Aartsen et al, Science, Nov 2013). Since then, there has been significant progress concerning both the experimental advancement and the theoretical interpretation of these data. In this talk, Galactic and extragalactic scenarios are reviewed taking into account most recent data and multimessenger modeling of the sources. In particular, it will be motivated in this paper that (a) both Galactic sources and gamma-ray bursts (at least in their prompt emission phase) are too weak to make up the total signal; (b) Starburst galaxies and active galactic nuclei are candidates that meet the criteria; (c) tensions between neutrino and gamma-ray data indicate that a larger fraction of the detected high-energy neutrinos actually might come from high-density regions in which both cosmic rays and high-energy photons are absorbed.