"A QR code (or Quick Response code) is like a bar code, in that it can be scanned with a reader and it will present some information based upon what is held within the code. In the case of a bar code it is normally a number which corresponds with a product or ISBN number or similar. In the case of a QR code, different types of information can be held within them:
URL (website address)
Email address
Phone number
Text
vCard
SMS
YouTube clip
Facebook profile
Wi-Fi details
Twitter profile
Map coordinate"