Various Solutions of the Atmospheric Neutrino Data

Various solutions of the atmospheric neutrino data are reviewed. Apart from orthodox two flavor $\nu_\mu\leftrightarrow\nu_\tau$ oscillations and three flavor oscillations, there are still possibilities, such as four flavor oscillations with the (2+2)- and (3+1)- schemes, a neutrino decay scenario and decoherence, which give a good fit to the data.