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A QR Code (it stands for "Quick Response") is a cell phone readable bar code that can store website URL's, plain text, phone numbers, email addresses and pretty much any other alphanumeric data.
Storing up to 4296 characters they are internationally standardised
under ISO 18004, so a QR code is a QR code all over the world -
they've been big in Japan forever, broke into Europe and the UK a few
years back, and are now getting real traction in USA.