Amazon has unveiled its first handset, calling it the Fire Phone. The device features a side-button that activates Firefly, an app that allows it recognize text, images and sound in the smartphone’s immediate vicinity. It can be used to bring up information – for example details of a wine, or the name of a song – and when relevant, the chance to buy a copy from Amazon. The company’s chief executive Jeff Bezos announced the device at a press conference in Seattle. The launch comes at a time when Amazon’s tablet sales appear to be on the wane, despite recent price promotions.