The basic idea is to immerse a user inside an imaginary, computer-generated "virtual world." Although many different technologies can be used to achieve this effect, they all share a common result: the user is cut off from any view of the real world outside. Much less attention has been paid to the field of Augmented Reality, although its potential is at least as great as that of Virtual Environments. In Augmented Reality, the user can see the real world around him, with computer graphics superimposed or composited with the real world. Instead of replacing the real world, we supplement it. Ideally, it would seem to the user that the real and virtual objects coexisted.

The head-mounted display used in augmented reality systems will enable the user to view superimposed graphics and text created by the system. As of today, the technology nearest to augmented reality head mounts is one that is being used in virtual reality applications. There are two basic head mount design concepts that are being researched for augmented reality systems and these are the video see-through systems and optical see-through systems. The video see-through systems block out the user's view of the outside environment and play the image real time through a camera mounted on the head gear. The main problem with this type of system is the delay in image adjustment whenever the user moves his head. Optical see-through systems, on the other hand, make use of technology that "paints" the images directly onto the user's retina through rapid movement of the light source. Though this system has its drawbacks, particularly its high price, researchers are confident that this system will be a lot more portable and less inconspicuous for future augmented reality systems.

n 1990, Boeing researcher Tom Caudell first coined the term “augmented reality” to describe a digital display used by aircraft electricians that blended virtual graphics onto a physical reality. As for the computer science world’s definition of augmented reality (AR) though, it’s more detailed, but essentially the same: Augmented reality is the interaction of superimposed graphics, audio and other sense enhancements over a real-world environment that’s displayed in real-time.AR is not a new concept either. In fact, we’ve seen it in many different ways over the years, but we just might not have noticed. From the yellow first-down lines sketched over a televised football game to the movie Who Framed Roger Rabbit—or even examples as basic as where a projector’s been used to project images atop a real setting—all are examples of virtual graphics being superimposed upon a real-life situation.

One of the most promising aspects of augmented reality is that it can be used for visual and highly interactive forms of learning, allowing the overlay of data onto the real world as easily as it simulates dynamic processes. A second key characteristic of augmented reality is its ability to respond to user input. This interactivity confers significant potential for learning and assessment. Augmented reality is an active, not a passive technology; students can use it to construct new understanding based on interactions with virtual objects that bring underlying data to life. Dynamic processes, extensive datasets, and objects too large or too small to be manipulated can be brought into a student’s personal space at a scale and in a form easy to understand and work with. In a broader context of education, augmented reality is appealing because it aligns with situated learning.

Augmented reality is changing the way we view the world -- or at least the way its users see the world. Picture yourself walking or driving down the street. With augmented-reality displays, which will eventually look much like a normal pair of glasses, informative graphics will appear in your field of view, and audio will coincide with whatever you see. These enhancements will be refreshed continually to reflect the movements of your head. Similar devices and applications already exist, particularly on smartphones like the iPhone.

A person who wishes to experience a learning session via augmented reality would don a pair of see-through glasses that also host two tiny video cameras and a pair of earphones. A tiny computer, perhaps worn on the wrist or around the waist, would recognize the geometry and content of the user's immediate environment and overlay that environment with meaningful images and sounds for a specific purpose. From the user’s point of view, he or she would apparently see and hear other people, objects, or events taking place right in front of or around them. These augmented perceptions would appear to be completely real. In technical terms, they would be rendered by the wearable computer with light shading that takes into account both the ambient and directional light sources found in the user's immediate environment. Put simply, the augmented reality system is "projecting" people, objects, environments or other elements onto the environment around you.

he 2010 Horizon Report includes examples of augmented reality like the Wii under the category Gesture Based Computing. Gesture recognition enables humans to interact with mechanical devices using simple natural gestures. In the future, the use of a keyboard, a mouse or even a touch pad may become a thing of the past with innovations in gesture based computing. See a video slide show of The New Media Consortium/ Educause report Click Gesture-Based Computing : 2010 NMC Horizon Report iPhone geotags. Geotagging and Geolocation Another important part of augmented reality applications is the use of geotagging and geolocation. A Geotag is a GPS coordinate that associates content such as videos, textual information, audio or any user- generated content to a specific location. When photographers use digital cameras, they have the choice to date stamp the video or photo. A Geotag is similar to that type of tag. AR applications draw on specific tags created by companies but will also depend on content that everyday users add through Geotagging. When we go to Google Earth to view a location, we are now able to find pictures and information added by users through these types of tags. Marker vs Markerless Augmented Reality AR Marker QR Code. AR Marker QR Semacode. Currently, many people associate augmented reality with black and white squares that trigger augmented reality elements. These black and white squares are called markers. Markers are also called QR (Quick Response) codes or Semacodes. A QR code is a two dimentional bar code that allows its content to be decoded at high speed. Markerless technology requires no marker to know the position of the object or person. Smartphone browsers that layer information over live locations are often considered in the markerless category, although they still use embedded "marked" information through geolocation and geotagging. The goal is to have augmented reality work much like this HP commercial Jerry Seinfeld for HP

Augmented Reality is important in education for a number of reasons: The real world can be annotated. Location information can be available in places or on objects Users can interact with virtual and physical objects at the same time. User can see virtual model from all angles. User can experiment/practice with virtual objects in a realistic but no consequence situation. (For example, practice surgery, firefighting) Engagement- rich information engages user -appeals to different learning styles

Augmented reality (AR) is a term for a live direct or an indirect view of a physical, real-world environment whose elements are augmented by computer-generated sensory input, such as sound or graphics.