  The presence of light sterile neutrinos is one of the unanswered questions of
particle physics. The cosmological counterpart is represented by dark
radiation, i.e.\ any form of radiation present in the early Universe besides
photons and standard (active) neutrinos. This short review provides a
comprehensive overview of the two problems and of their connection. We review
the status of neutrino oscillation anomalies, commenting on the most recent
oscillation data and their mutual tensions, and we discuss the constraints from
other terrestrial probes. We show the shortcomings of translating light sterile
neutrinos in cosmology as additional thermalised relativistic species, produced
by neutrino oscillations, and we detail alternative solutions, specifically
focusing on neutrino non standard interactions, and on their link to the Hubble
constant problem. The impact of a new force leading to dark radiation -- dark
matter interactions is also discussed in the realm of new physics in the dark
sector.
