Discovery of atmospheric neutrino oscillations**

Atmospheric neutrinos are produced by cosmic ray interactions in the atmosphere. The zenith‐angle and energy dependence of the muon‐ and electron‐ neutrino events are observed in atmospheric neutrino experiments. Through these studies neutrino oscillations were discovered. In this article, studies of atmospheric neutrinos in the Kamiokande and Super‐Kamiokande experiments are described.