QR code stands for Quick Response code.
It is a machine-readable optical label containing information.
This information is often a link that points to a website or app.
The label consists of black and white squares on white background.
Uses of QR codes are not only limited to
- augmented reality
- restaurant ordering
- vcard contacts
- wi-fi networks login
There’s even a section about the COVID-19 pandemic on the Wikipedia QR code site
Techincally there are so called “Tracking boxes” embedded in the QR code.
Depending on the size/resolution of the image, there may be more “Tracking boxes” for improved error correction.
There are four levels of error correction capability.
Because of this capability, it is possible to create artistic QR codes that still scan correctly, but contain intentional errors to make them more readable or attractive to the human eye, as well as to incorporate colors, logos, and other features into the QR code. See Error correction on Wikipedia