[en] CORSIKA is a detailed Monte Carlo program to study the development of extensive air showers in the atmosphere initiated by photons, protons, or nuclei of energies up to 10¹⁷ eV. Wherever possible experimentally accessible data have been used to model the high energy interactions of primary and secondary particles with the nuclei of the atmosphere. The CORSIKA code is based essentially on the Dual Parton Model to describe the hadronic interactions at high energies, the isobar model for hadronic reactions at low energies, and EGS4 for a detailed simulation of the electromagnetic part. The nucleus-nucleus interaction model follows the considerations of Klar and Huefner. Heuristic nucleus fragment models are implemented. Diffractive and charge exchange reactions are possible. Photoproduction of muon pairs and hadrons has been introduced into the electromagnetic part. The gross features of the program are presented and some results are given