Virtual reality
Around the same time, Douglas Engelbart used computer screens both as input and output devices. In 1968, Ivan Sutherland, with the help of many students including Bob Sproull, created what was widely considered to be the first head-mounted display (HMD) system for use in immersive simulation applications. It was primitive both in terms of user interface and realism, and the HMD to be worn by the user was so heavy that it had to be suspended from the ceiling. The graphics comprising the virtual environment were simple wire-frame model rooms. The formidable appearance of the device inspired its name, The Sword of Damocles.
HTC Vive
In July 2016, VR news website Road to VR used game session figures from the Steam VR platform to estimate that approximately 100,000 Vive headsets had been shipped since launch. In the same month, SensoMotoric Instruments (SMI), a computer vision company, integrated its eye tracking technology in the HTC Vive to turn it into a dedicated eye tracking solution for research and professional applications. In November 2016, Vive announced that it would begin the first retail sales of its headsets at JB Hi-Fi and Harvey Norman stores in Australia later that month.