The Glashow resonance describes the resonant formation of an on-mass W- boson via the scattering of an electron antineutrino and an electron, a process first predicted in 1959. In the electron rest frame, the requisite neutrino energy of 6.3 PeV lies beyond the reach of terrestrial accelerators. However, the discovery of a diffuse flux of astrophysical neutrinos by IceCube gave rise to the possibility of detecting the resonance via high-energy (anti)neutrinos from outer space.