How QR Codes Work: Technology and Scanning Explained
The Structure of a QR Code
A QR code is made of a grid of small squares (modules). Certain areas are reserved for finder patterns (the three large squares in the corners), alignment patterns, timing patterns, and the actual data. The rest of the grid encodes the message in binary form.
Error correction is built in: even if part of the code is dirty or damaged, it can often still be read. QR codes support four levels of error correction from about 7% to 30% of the code surface, so you can choose a balance between capacity and robustness.
How Your Phone Reads a QR Code
When you point your camera at a QR code, the device locates the three finder patterns, figures out the orientation and size, then decodes the grid into bits. The bits are converted back into the original data (e.g. a URL), and the phone can then open the link, show text, or connect to Wi‑Fi.
No internet is required to decode the pattern; only when the content is a URL does the phone need connectivity to load the page.