How QR codes work
A QR code encodes text as a grid of modules with built-in error correction, so codes stay scannable even when partially obscured or printed small. URLs, WiFi credentials, contact cards, and plain text are the most common payloads.
Tips for scannable codes
Keep the payload short — long URLs produce dense codes that are harder to scan at a distance. Maintain a quiet white margin around the code, and test on a real phone camera before printing.