This document discusses augmented reality (AR) and defines it as a technology that overlays computer-generated imagery on real-world views in real-time, allowing digital content to be integrated with the physical environment. AR combines real and virtual worlds through real-time interaction and accurate registration of virtual and real objects. The document also lists some key characteristics of AR and provides examples of different types of AR including marker-based, marker-less, location-based, projection-based, and contour-based AR. Finally, it discusses some benefits of AR such as enhanced learning and motivation as well as tools that can be used to develop AR applications.