Radioactivation analysis is based upon irradiation of nuclei with elementary particles. In many cases the interaction gives rise to radioactive nuclei, which can be detected and identified by the emitted radiation. If we irradiate under identical conditions an unknown quantity of a certain atomic species and a known quantity of the same species, the following relatio will exist between the induced radioactivities and the irradiated masses: $frac{Activity standard}{activity unknown}$=$frac{Mass standard}{Mass unknown}$ From this equation the mass of the unknown can be easily calculated. This relatively siple technique (abstract made from the irradiating facility) allows quantitative determination of about 60 elements with a sensibility that most of the time considerably exceeds the sensibility of conventional analysis techniques. General review articles from Gordon and Meinke should be consulted for further detail.