This tutorial will survey single event effects (SEE) induced by terrestrial cosmic rays on current commercial CMOS technologies. After describing the natural radiation environment at ground and atmospheric levels, the tutorial will describe the physics of SEEs, from the main mechanisms of interaction between atmospheric radiation (neutrons, protons, muons) and circuit materials to the electrical response of transistors, cells and complete circuits. SEE characterization using accelerated and real-time tests will be examined, as well as modeling and numerical simulation issues. Special emphasis will finally concern the radiation response of advanced technologies, including deca-nanometer bulk, FD-SOI and FinFET families.