They are easy to use for marketing, they are new & they are hot.
Started from Japan, the QR code has now spread across whole world, the significant contributor to this revolution are many great applications on iPhone, android phones, smartphones, or computer, which can extract the information out of simple black & white squares.
Why not you yourself do the fun, trace out the QR Code below, if needed, the links are given below for your reference :
More Resources & useful links :
Wikipedia of QR Code :
How to read QR Code in Ubuntu :
How to read QR Code from your PC :
How to read QR Code on your iPhone :
QR Code for Nokia Phones :
How to generate your QR Code :
1) From Kaywa :
2) From neoReader :