  The IceCube project transformed a cubic kilometer of transparent, natural
Antarctic ice into a Cherenkov detector. It discovered neutrinos of TeV-PeV
energy originating beyond our Galaxy with an energy flux that exceeds the one
of high-energy gamma rays of extragalactic origin. Unlike at any other
wavelength of light, extragalactic neutrinos outshine the nearby sources in our
own Milky way. Updated measurements of the diffuse cosmic neutrino flux
indicate that the high-energy gamma rays produced by the neutral pions that
accompany cosmic neutrinos lose energy in the sources and are likely to be
observed at MeV energy, or below. After the reanalysis of 10 years of archival
data with an improved data selection and enhanced data analysis methods, the
active galaxy NGC 1068 emerged as the hottest spot in the neutrino sky map. It
is also the most significant source in a search at the positions of 110
preselected high-energy gamma-ray sources. Additionally, we find evidence for
neutrino emission from the active galaxies PKS 1424+240 and TXS 0506+056. TXS
0506+056 had already been identified as a neutrino source in a multimessenger
campaign triggered by a neutrino of 290 TeV energy and, by the independent
observation of a neutrino burst in 2014 from this source in archival IceCube
data. The observations point to active galaxies as the sources of cosmic
neutrinos, and cosmic rays, with the gamma-ray-obscured dense cores near the
supermassive black holes at their center as the sites where neutrinos
originate, typically within $10\sim100$ Schwarzschild radii.
