QR Codes(Quick Response Codes) are just barcodes. There is nothing fancy about them.
Just like the grocery store clerk uses barcodes to look up the product and scan the price into the computer, your mobile device or computer can look up QR codes to:
take you to a website,
read some text,
give you a phone number,
or generate a text message.
QR Codes are barcodes of information that hardlink the physical world with the online world. They are considered a form of simple augmented reality.
Via Gumersindo Fernández, Juan Arbulu