Although initially used for tracking parts in vehicle manufacturing, QR Codes are now used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile phone users (known as mobile tagging).
QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards, or on just about any object about which users might need information. Users with a camera phone equipped with the correct reader application can scan the image of the QR Code to display text, contact information, connect to a wireless network, or open a web page in the phone’s browser. This act of linking from physical world objects is known as a hardlink or physical world hyperlinks. Google’s mobile Android operating system supports the use of QR codes by natively including the barcode scanner (ZXing) on some models and the browser supports URI redirection, which allows QR Codes to send metadata to existing applications on the device. Nokia’s Symbian operating system is also provided with a barcode scanner, which is able to read QR Codes, while mbarcode is a QR code reader for the Maemo operating system. In the Apple iOS is not natively included, but some iTunes Apps, for free, are available with reader and metadata browser URI redirection.
QR Codes can be used in a number of ways, to display text to the user, to add a vcard contact to the users device, to open a URI or to compose a text message or email. Users can also generate and print their own QR Code for others to scan and use by visiting one of several free QR Code generating sites.
The large QR Code above has a message from Deskarati embedded for you. The smaller one is a little less altruistic.
With thanks to Wikipedia