Understanding QR code technology

A QR code is a two-dimensional barcode that encodes data as a grid of black and white modules. Built-in error correction means a code can still scan correctly even if part of it is damaged or obscured — useful for anything printed and handled repeatedly.

A static QR code encodes its destination directly, so changing that destination means reprinting the code. A redirect-based code instead points at a short URL that a server resolves — the printed code never changes, only where it points.