They are 2D barcodes that can be decoded by most smartphones that have a camera.
It can be as simple as a link to a website, or as complex as a MECard/VCard format that can allow the person who scans the code to save your full contact information to their address book with a single click.
That is virtually limited only by your imagination. They can be printed on you business cards so the person can scan your information into their phone address book. They can be printed on postcards and flyers to offer discounts or links to website.
QR Codes were created in 1994, but only recently have they started to be popular in the United States. Looking for more info. about the origin of the “Quick Response” Code.. check out Wikipedia. Then give us a call to see how we can help you get started with your projects.