The holodeck is an immersive virtual reality environment that was featured on Star Trek, a popular science fiction television and film series of the late 20th century.
Although Star Trek’s fictional technology is still in advance of what is currently possible, the holodeck serves as a good example of the far end of the virtuality continuum: A virtual reality that completely replaces the user’s environment in such a way that it is indistinguishable from what they might experience in the physical world – although it could also include elements that don’t exist in reality. To achieve that affect, a VR environment would have to enable unconstrained user movement and provide realistic stimuli for all the human senses.
The holodeck first appeared in 1974 in an animated Star Trek series, although it was originally just called a recreation room. Subsequently, Star Trek: The Next Generation featured the holodeck frequently, where it provided the opportunity to put the characters in environments and situations that could not otherwise be presented, such as historical events on Planet Earth.
Watch a video about a real-life approximation of the holodeck: