Mobile QR codes or 2d codes as they are known may be a mystery to you. They are rectangles that have a whole sequence of smaller rectangles inside. They make a code that can be scanned by the camera on many mobile phones. Once scanned they can take you to a website address on the phones browser, they can add address book details to your phone or do many other cools things. Be on the lookout for them. I am sure you will see them soon.