QR Codes allows you to send information to friends with encrypted images or helps advertisers to communicate their website links to their customers.
QR Codes is a
novel way to communicate text, links and other information inside coded images. The user can send an URL, Text, Phone Number or SMS in a coded black and white image to their friends. The black and white images doesn’t make any sense to the naked eye, but QR program can convert them back to text or link from which these images are derived.
The user with a suitable QR code decoder program built in their phone or computer will then convert this coded image back to the main message (URL or text or any information). The same program recognizes the link and launches the mobile browser in the QR Codes.
There is another iPhone application QR Code Decoder from Italy based
iMatric can open web links via Safari, add contact in the address book, add event in the Calendar, add a new note to Notes and initiate a new e-mail or phone call from the QR Codes.
Unlike a bar code which can store only in one direction, the QR code can be stored in X & Y directions and thus have more storage capacity per unit area.

Labnol.org
QR Code vs Barcode
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Here is a sample code and message.

Labnol.org
QR Code Decodes Messages
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Denso Wave, introduced this QR Codes concept, said the QR codes are readable from any direction and data stored inside QR Codes can be restored even if the image is partially damaged.
The QR Codes are becoming popular in Japan as shown in one of the video, how easily it is to get a link of the business from the advertisement billboard. This system is also being tested in the U.S.
To generate QR Codes, use this simple application from
Kawya, a web based QR Code generator. For decoding the images, we need to download a
Java app for desktop or a
Java reader for the mobiles.
If you like to make your own QR Codes, go to Kawya - a web based QR code image generator. Now to decode these QR images, download a small Java app for desktop or get this reader if you have a Java enabled mobile phone like Nokia, Sony Ericsson, etc.
And finally there is a
Firefox add-on that helps you convert web pages to QR images.