The International Stereoscopic Union (ISU) is an international 3D association. Founded in May 1975, the ISU is a club of 3D enthusiasts as well as a club of stereo clubs. The ISU's members currently number over 1,050 and come from 41 countries. 3D photography, 3D video imaging, computer stereo, holography, virtual reality and other stereoscopic photography techniques are used by members of the ISU. The quarterly journal of the ISU, Stereoscopy - the publication of 3D image-makers, is circulated to members. Apart from tuition in 3D photographic techniques, the Journal carries information and articles from around the world on new equipment, literature and all manner of related subjects. Many articles are illustrated with large 3D drawings and stereo photos. Since Issue 1/2007, Stereoscopy has been published in full color. A major activity of the ISU is the organization of a Congress every second year in one of the major member countries.