  This essay, written in 1998 by an active participant in both virtual reality
development and the virtual reality definition debate, discusses the definition
of the phrase "Virtual Reality" (VR). I start with history from a personal
perspective, concentrating on the debate between the "Virtual Reality" and
"Virtual Environment" labels in the late 1980's and early 1990's. Definitions
of VR based on specific technologies are shown to be unsatisfactory. I propose
the following definition of VR, based on the striking effects of a good VR
system: "Virtual Reality is the use of computer technology to create the effect
of an interactive three-dimensional world in which the objects have a sense of
spatial presence." The justification for this definition is discussed in
detail, and is favorably compared with the dictionary definitions of "virtual"
and "reality". The implications of this definition for virtual reality
technology are briefly examined.
