QR Codes:

if you want to experiment with QR codes, you'll need a couple of tools.

First, install a QR scanner app on your smartphone. Search the Web for "QR Reader" and the model of your phone to find a scanner app; they're available for the iPhone, Windows Mobile, Nokia, BlackBerry, and other app-based phones with a camera built in. "I-nigma" and "Barcode Scanner" are two such apps you can download for free.

Once you've got a scanner installed, point it at one of these codes to give it a try: