QR codes provide a fast link between the physical and digital worlds by allowing smartphone users to scan a QR code to access online content. They are becoming increasingly popular, with over 50 million smartphones in the US and projections of over 150 million by 2013. Businesses can use QR codes for marketing purposes like promotions, coupons, and event registration to engage customers. The types of content that can be accessed through a QR code scan include web pages, maps, music, pictures, videos, text, and contact information.