Virtual reality
Virtual reality (often just called VR) is the name for computer technology that makes a person feel like they are somewhere else. It uses software to produce images, sounds, and other sensations to create a different place so that a user feels like he or she is really part of this other place. That other place can be a real place (to take a tour in another country, for instance) or imaginary (playing a game).
A user uses a headset which consists of a screen to project the content, and speakers to produce sounds. The technology to do this needs special display screens or projectors and other devices. Often the picture will change when the user moves their head, they may be able to "walk" through this virtual space and to see things in that space from different directions, and maybe move things in that space. Haptic feedback might also be used to help make it seem more real - haptic feedback uses special gloves that make it feel like you touched something in real life.
Virtual reality is different than augmented reality, which shows the real place that a person is in, but changes or adds to it. Pokémon Go is an example of augmented reality. Augmented reality headsets are also commercially available such as the Microsoft HoloLens.
Virtual Reality Media
Researchers with the European Space Agency in Darmstadt, Germany, equipped with a VR headset and motion controllers, demonstrating how astronauts might use virtual reality in the future to train to extinguish a fire inside a lunar habitat
A Missouri National Guardsman looks into a VR training head-mounted display at Fort Leonard Wood in 2015.
View-Master, a stereoscopic visual simulator, was introduced in 1939.
NASA Ames's 1985 VIEW headset
A VPL Research DataSuit, a full-body outfit with sensors for measuring the movement of arms, legs, and trunk. Developed c. 1989. Displayed at the Nissho Iwai showroom in Tokyo
Virtual Fixtures immersive AR system developed in 1992. Picture features Dr. Louis Rosenberg interacting freely in 3D with overlaid virtual objects called 'fixtures'.
An inside view of the Oculus Rift Crescent Bay prototype headset