How Do QR Codes Work?

QR codes work by arranging dark and light squares in a pattern that a camera or scanner can decode into text, a link or another type of stored data.

The basic scanning process

When a phone scans a QR code, it identifies the square pattern, corrects the angle, reads the encoded data and then offers the user an action. That action may be opening a website, joining WiFi, creating a contact, writing an email or displaying text.

The three larger corner squares help the scanner detect the code’s position and orientation. Other parts of the design contain format, version and error-correction information.

Static QR codes

A static QR code stores the final information directly inside the code. If the code contains a website address, that address is fixed. To change the destination later, you normally need to create and print a new code.

Dynamic QR codes

A dynamic QR code usually points to a short redirect URL. The redirect destination can be changed later by the provider. Dynamic QR codes can support tracking, but they depend on the provider continuing to run the redirect service.

Why error correction matters

QR codes include error correction, which means they may still scan even if part of the pattern is damaged or visually altered. Higher error correction can make a code more resilient, but it can also make the pattern denser.