Google Glass was a type of wearable technology with an optical head-mounted display (OHMD). It was developed by Google[9] with the mission of producing a mass-market ubiquitous computer.[1] Google Glass displays information in a smartphone-like hands-free format.[10] Wearers communicate with the Internet via natural language voice commands.[11][12] Google started selling a prototype of Google Glass to qualified "Glass Explorers" in the US on April 15, 2013, for a limited period for $1,500, before it became available to the public on May 15, 2014,[13] for the same price.