'Virtual Reality' was a term first coined by
Jaron Lanier in 1989 to refer to 'Immersive Virtual Reality'. IVR involves the user becoming totally sensually immersed in a computer-generated
3D world.
There are two main ways of immersing a user in a virtual world. One is by using a Head-Mounted Display, which is a sort of helmet that slips on a user's head with a display visor, and the other is CAVE - stereo images projected onto the walls of a room, and a head tracker to move the point of reference.
IVR aims to provide a totally convincing virtual world that could have a variety of applications - training, treatment of phobias, and of course entertainment. VRML is a web scripting language which allows users to make homepages that are in fact 3D spaces with integrated hyperlinks. These worlds are usually modelled with a monitor and mouse however, and are therefore not fully immersive.