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 \nu_\mu-->\nu_\tau channel provides an excellent 2\nu fit to the data, one cannot exclude, at present, the occurrence of additional subleading \nu_\mu-->\nu_e oscillations (3\nu schemes) or of sizable \nu_\mu-->\nu_s oscillations (4\nu 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.