Virtual art is a term for the virtualization of art, made with the technical media developed at the end of the 1980s (or a bit before, in some cases). These include human-machine interfaces such as visualization casks, stereoscopic spectacles and screens, digital painting and sculpture, generators of three-dimensional sound, data gloves, data clothes, position sensors, tactile and power feed-back systems, etc. As virtual art covers such a wide array of mediums it is a catch-all term for specific focuses within it. Much contemporary art has become, in Frank Popper's terms, virtualized.