Augmented Reality (or short AR) refers to the computer based extension of reality perception. In general this additional information can extend any of the human sensory organs. Currently however most of the time the expansion of visual information is understood, that makes through superimposition additional information available. A well known example is during football broadcasts the superimposition of circles, lines and distance measurements by free kicks for the television viewer.
The reality-virtuality-continuum shows the gradual transition of the normal reality to the virtual reality and its intermediate steps from left to right.
Augmented reality and augmented virtuality are also called Mixed Reality because they contain both real and virtual elements.