The GEANT program describes the passage of elementary particles through the matter. Originally designed for the High Energy Physics experiments, it has today found applications also outside this domain in the areas of medical and biological sciencies, radioprotection and astronautics. The principal applications of GEANT in High Energy Physics are:
1. the tracking of particles through an experimental setup for simulation of detector response
2. the graphical representation of the setup and of the particle trajectories
http://wwwasd.web.cern.ch/wwwasd/geant/
