QR code can be consider as 2D bar code, created by Japanese. It has been used to encode URL and let camera photo to decode the URL stored in the 2D bar code.
You can read the following wiki if you want to know more. And if you own Sony Ericsson, Nokia or motorola phone, you may go to Kaywa Reader to see if your phone is supported by this scanner software.
Just try on the following QRCode :)