Augmented reality (AR) adds an additional layer of digital information to the real physical world. AR works in real-time and contextualizes information. The basic components are a trigger, lens, and new content. Common triggers include images, locations, sounds and text. When triggered, additional images, videos, text or 3D models are displayed. AR information is shown through devices like smart glasses, projectors or mobile apps. Future directions for AR include visual search using cameras to access information and user-defined triggers where any object can be tagged to display content.