Photo by CoCreatr
A QR Code (short for "Quick Response") is a barcode that contains data that can be read by a phone's camera. Most smartphones come equipped with software that allows them to download a QR Code reader. Once you download a reader, the phone's camera acts like a scanner, allowing it to "read" the barcode.
These codes, once scanned by your phone, can provide you with a URL, contact information, SMS, or similar links to information right on your phone. Think of it as a black and white link, or a heavily pixelated one.
In order to read a QR code, your phone needs to have a code reader. You can find a long list of readers to download to your phone (iPhone, Android, and more) at http://www.mobile-barcodes.com/qr-code-software/.
via cnet Australia: "This tutorial explains what you can do with QR codes, and suggests free mobile QR apps for the major phone operating systems so you can start using these small graphics to send or read links, contact information or just about any other information." A great basic video about QR codes.