How QR codes work isn’t terribly complicated. Here is a basic overview of how QR codes work:
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1. A QR code is a two-dimensional matrix barcode comprised of black and white shapes.
2. Codes can either be dynamic or static, with static meaning that the destinations can never be changed and dynamic meaning that they can since the data isn’t directly stored on the QR code.
3. When scanned or photographed by a smartphone, the camera app will decode the data from the QR code and display it on the screen. 
4. To read a QR code, you need to have an app that can scan them installed on your device.
5. All newly released smartphones have built-in QR readers so there’s no longer a need to download a QR reader app. 
6. Once scanned, depending on what type of information is stored within it, a variety of actions can be taken such as opening web pages, initiating text messages or making phone calls.