Abbey Web Design

They are called QR Codes. QR, short for Quick Response codes are similar to the standard barcode in that they represent information. The shape was designed to be scanned by a QR Scanner (an app) on a mobile device and convert the QR code into meaningful information. This information could be a website link, a link to a YouTube video, contact details, useful information, in fact anything you can think of within the limits of 4296 characters (for version 40).

It pays to be on your guard and only scan QR codes from trusted sources, otherwise you could end up on an unsavoury site or even worse pick up some free Malware. Read an article from The Register on how easy it could be to find yourself exposed.