Why QR codes work
QR codes pack up to ~3,000 bytes (roughly 2,900 ASCII characters, fewer for non-ASCII or dense content) into a square matrix readable by any phone camera. They're self-correcting: up to 30% of the pattern can be damaged and a phone can still decode it — that's the error correction level built in.
Tips from the real world
- Don't print tiny: on paper, the QR should be ≥ 2 × 2 cm for scanning at arm's length; on a screen, ≥ 200 px.
- Wi-Fi QR encodes
WIFI:T:WPA;S:name;P:pass;;— phones scan and join instantly, no typing. - Test before printing! Phone cameras handle most, but some apps choke on unusual characters.
- For URLs use the full https:// form — scanners don't guess protocols.