"Artificial Reality" was the term Myron Krueger used to describe his interactive immersive environments, based on video recognition techniques, that put a user in full, unencumbered contact with the digital world. He started this work in the late 1960s and is considered to be a key figure in the early innovation of virtual reality. His first book "Artificial Reality" was published in 1983 and updated in "Artificial Reality II" in 1991 (both published by Addison Wesley).