Learn what a QR code stores, how a scanner reads it, and why design and testing matter.
A QR code is a two-dimensional symbol made from light and dark modules. A camera captures the pattern, software locates its position markers, corrects the perspective, and decodes the stored data. That data might be text, a web address, contact details, a Wi-Fi configuration, or another supported format.
What is inside the symbol?
The familiar corner squares help a reader find and orient the code. Timing and alignment patterns help map the grid. Other regions carry format, version, data, and error-correction information. As the amount of data increases, the grid becomes denser. DENSO WAVE explains that QR Code versions run from Version 1 at 21 by 21 modules to Version 40 at 177 by 177 modules, with four modules added per side at each step.
Why two codes can look different
The same visible message can produce different patterns because of character encoding, error-correction level, mask selection, and generator settings. A different pattern is not automatically wrong. What matters is whether standards-compatible readers recover the intended content reliably.
Static and dynamic are service choices
A static code contains its final value. A dynamic code commonly contains a short URL controlled by a service, which redirects to a destination that can be changed. The printed image is still an ordinary QR code; the editable behavior comes from the web redirect.
Use a simple test routine
Scan the downloaded file, then test the final printed proof under realistic lighting and distance. Check the decoded value before opening it. For technical background, see the DENSO WAVE pages on QR Code basics and versions and capacity.