Analysis of oscillations of atmospheric neutrinos

We briefly review the current status of standard oscillations of atmospheric neutrinos in schemes with two, three, and four flavor mixing. It is shown that, although the pure νμ → ντ channel provides an excellent 2ν fit to the data, one cannot exclude, at present, the occurrence of additional subleading νμ → νe oscillations (3ν schemes) or of sizable νμ → νs oscillations (4ν schemes). It is also shown that the wide dynamical range of energy and pathlength probed by the Super-Kamiokande experiment puts severe constraints on nonstandard explanations of the atmospheric neutrino data, with a few notable exceptions.