(XR) is a term referring to all real-and-virtual combined environments and human-machine interactions generated by computer technology and wearables, where the 'X' represents a variable for any current or future spatial computing technologies. e.g. It includes representative forms such as (AR), (MR) and (VR) and the areas interpolated among them. The levels of virtuality range from partially sensory inputs to immersive virtuality, also called VR.
XR is a superset which includes the entire spectrum from "the complete real" to "the complete virtual" in the concept of introduced by . Still, its connotation lies in the extension of human experiences especially relating to the senses of existence (represented by VR) and the acquisition of cognition (represented by AR). With the continuous development in , this connotation is still evolving.