The document discusses augmented reality and its relationship to other types of mixed reality technologies. It defines augmented reality as overlaying digital information and content onto the real world. This is in contrast to virtual reality, which immerses users in a simulated environment, and augmented virtuality, which overlays real world information onto virtual worlds. The document also references several sources that provide further information on augmented reality definitions, taxonomies, surveys, and design considerations for augmented reality experiences.