Augmented reality involves drawing 3D geometry onto real world scenes. This is usually achieved by layering graphics onto a video feed. It can be useful for training applications because for example labels could be added to an automotive engine or pipework positions layered into a new development. More educational applications could be pop up books for children etc.
The origin of the word augmented is augment, which means to add something. In the case of augmented reality (also called AR), graphics, sounds, and touch feedback are added into our natural world. Unlike virtual reality, which requires you to inhabit an entirely virtual environment, augmented reality uses your existing natural environment and simply overlays virtual information on top of it. As both virtual and real worlds harmoniously coexist, users of augmented reality experience a new and improved world where virtual information is used as a tool to provide assistance in everyday activities.
Applications of augmented reality can be as simple as a text-notification or as complicated as an instruction on how to perform a life-threatening surgical procedure. They can highlight certain features, enhance understandings, and provide accessible and timely data. Cell phones apps and business applications are a few of the many applications driving augmented reality application development. The key point is that the information provided is highly topical and relevant to what you want you are doing.