The Growth of AR Browsers Since the fi rst AR browser fi rst appeared in 2008, the genre has grown to around 300 applications available for the iPhone alone. At last count, an average of 20 new iPhone applications that exhibited AR browser behavior were being added to the iPhone App Store each month. Many of these applications combine geo-location and the camera with freely available APIs from Wikipedia, Twitter, Flickr, Google Search, or an untold number of other sources to enable users to visualize the locations of POIs around them. There are applications that, for example, help you see who is tweeting around you, help you fi nd your nearest train station, or help you fi nd a place to eat. Since this book is about building for the popular platforms rather than building applications from scratch, you can relax a little because a lot of the plumbing is taken care of. You won’t need to worry about APIs necessary to detect the user’s location, what design is best for building a user interface, or even how to fi gure the movement of the user’s devices. In most cases, you need only to supply the XML that contains the coordinates of the POI along with relevant icons and text. The diffi cult choice is determining which platform to build for.