What is QR Code?
A QR Code is a matrix code (or two-dimensional bar code)
The "QR" is derived from "Quick Response", as the creator intended the code to allow its contents to be decoded at high speed.
QR Codes are now used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile phone users (known as mobile tagging). QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards or just about any object that users might need information about. Users with a camera phone equipped with the correct reader software can scan the image of the QR Code causing the phone’s browser to launch and redirect to the programmed URL.
Cited from Wikipedia
How to read QR Code?
Any person with a cell phone that has the QR code reader software installed can shoot a picture of that image and they will be taken to the website for that code.