A QR code is a barcode that that generally contains alphanumeric information and takes you to a website when you read the QR code with your smartphone (i.e. by taking a picture of it with a QR reader app).
QR codes remind me of the barcodes in the store at the checkout line, but QR codes look more like a squared-off roschach test compared to the barcodes on items you purchase which are rectangular straight lines from top to bottom.
By reading the QR code, you don't have to remember or type any information into your smartphone--your just zipped right off to wherever the QR points you (usually after you confirm on the screen that you are okay with going to the URL).
But QR codes like with any information technology, can be used for good or evil -- for some reason though people seemed to have been unsuspecting of the sort of innocuous looking QRs.
Kaspersky Lab has issued a warning on QR codes after finding consumers in Russia scammed when they thought they were downloading an Android app and where instead infected with malware that caused them to send SMS messages to a premium number that charged for each message sent.
So while QR codes can take a reader to a harmless website for information, like other computer code, they can contain instructions that cause you to send email, SMS messages, download applications, etc.
So unless you know what you are QR reading (i.e. you have a high-degree of confidence in whoever placed the advertisement with the QR code)--think twice before scanning that barcode, because you may get a surprise package in your smartphone that you weren't expecting causing infection of your device, loss of privacy to the information stored on it, or costing you money for things you never wanted or intended to spend on.
Scanning a QR code while as simple taking a picture of a sunset--may not have as beautiful consequences.
(Source Photo: here)