2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/7931We present an introductory lecture on general features of cosmic rays, for non-experts, and some recent developments concerning cascade equations for air shower developments.invited talk, presented at the Hadron-RANP2004 workshopAstrophysicsHigh Energy Physics - PhenomenologyNuclear TheoryUltra-High Energy Cosmic Rays: Some General Features, and Recent Developments Concerning Air Shower Computationstext