What is a QR code? How it works, in plain words

The squares have different jobs

The large corner patterns help a camera locate and orient the code. Smaller alignment and timing patterns help it map the grid. The remaining modules store the encoded data and error-correction information.

A QR version adds four modules per side as it grows. More content usually means a denser pattern, which needs sharper reproduction and more room to scan.

• Keep a clear margin around the outside.
• Use a dark foreground on a light background.
• Avoid stretching the square into a rectangle.

Error correction helps with damage

QR codes include redundant data so a scanner can recover from some dirt, folds or obstruction. Higher correction levels add redundancy and can also make the code denser.

A logo does not make a code unbreakable. It covers data modules, so its size and position matter. Test the exported image and a physical sample.

What happens when you scan

The camera decodes the text stored in the pattern. A phone may then offer an action such as opening a web address, joining Wi-Fi, or saving a contact. Review the destination before accepting the action.

A QR code does not inherently connect to a tracking service. The content can be a direct static value or, if its maker chose one, a URL that redirects elsewhere.