  Light sterile neutrinos with a mass around 1 eV have been studied for many
years as a possible explanation of the so called short-baseline neutrino
oscillation anomalies. Recently, several neutrino oscillation experiments
reported preferences for non-zero values of the mixing angles and squared mass
differences for active-sterile mixing, which however are not always in
agreement. I will review our current knowledge on the light sterile neutrino in
the 3+1 model, starting with a separate discussion on the status of the most
relevant searches and then analyzing the problems that arise when combining
different probes in a global fit.
