Estimation of reactor neutrino fluxes

Reactor antineutrinos have been indispensable for our understanding of neutrino mass and mixing. At the same time, discrepancies between the observed and predicted reactor $\overline{\nu}_{e}$ rate and energy spectra have grown as the precision of these measurements has improved. Measurements of the electrons emitted following fission result in the most precise predictions for the corresponding $\overline{\nu}_{e}$ flux, and our understanding of the potential systematic differences between the fission $e^-$ and $\overline{\nu}_{e}$ fluxes has improved. Measurements of individual fission daughter isotopes and their decays are fraught with uncertainties, yet still provide insight into these discrepancies. Detailed comparisons of $\overline{\nu}_{e}$ measurements among reactors are also shedding new light on this topic.