Picture this: As your eyes alight for the first time on a skyscraper in a foreign cityscape, a disembodied voice whispers in your ear the phone number of a posh bar on the top floor.

Or this: You have been spotted on the street by an old friend whose name suddenly eludes you. But even before there is time to shake hands, a glance at your smartphone reveals her identity and the date of your last encounter.

Welcome to the world of augmented reality, the here-and-now enhancement of everyday experience through virtual, interactive technology.