The International Union of Radio Science (universally referred to as URSI) is one of the majority of Scientific Unions which adhere to the International Council of Scientific Unions (ICSU). It was created in 1919, during the Constitutive Assembly of the International Research Council (now ICSU) at the same time as the International Unions of Astronomy (IAU), of Geodesy and Geophysics (IUGG), and of Pure and Applied Chemistry (IUPAC). URSI's origins go back even further than 1919 because it was essentially a change in name of the earlier Commission Internationale de Telegraphie sans Fil, which had been active during the period 1913-1914 when the only existing type of radio communication system was radiotelegraphy.
The original objective of URSI in 1919 (to encourage "scientific studies of radiotelegraphy, especially those which require international cooperation") has, over the past 75 years, been broadened to include all radio science, from telecommunications to radio astronomy, and covering the frequency range from ELF to optical.
In the context of the present activities of URSI, the term "radioscience" includes not only the transmission of information from a transmitter to a distant receiver, but also the acquisition of information about distant passive objects by the use of radar techniques, studies of the radiation stimulated or spontaneously emitted by these objects, and active modification of objects by powerful radio waves. Radio remote sensing techniques have been widely applied in research in geographical, geophysical and other branches of science. In astronomy, celestial bodies and ionized regions are investigated through study of their radiofrequency emissions and effects (dispersion, polarization) on propagation. Much of space research involves passive and active experiments on or using radio waves from ELF to LF and much also depends on the applications of radio techniques in communication, sensing and control.