QR codes are on restaurant menus, event tickets, invoices, advertising and even vaccination records. They are squares of dots that your phone reads instantly. But what is behind that pattern?
What QR means
QR = Quick Response. It was invented in 1994 by Denso Wave, a Toyota subsidiary, to track car parts on the assembly line. Its key feature: it reads much faster than a linear barcode and stores far more information.
What a QR stores
A QR is a 2D data container. The most common types:
| Type | Example content |
|---|---|
| Text | Hello world |
| URL | https://example.com |
| Contact (vCard) | Name, phone, email, address |
| Wi-Fi | WIFI:T:WPA;S:MyNetwork;P:password;; |
| SMS | SMSTO:+34600123456:Hello |
MATMSG:TO:mail@example.com;SUB:Subject;BODY:Body;; |
|
| Geolocation | geo:40.4168,-3.7038 |
When you scan a QR, your phone detects the type and opens the corresponding app (browser, contacts, Wi-Fi settings, etc.).
Visual structure of a QR
The pattern has fixed parts the reader looks for to orient itself:
- Three eyes (finder patterns) in the top-left, top-right and bottom-left corners: they define orientation.
- Timing patterns (alternating lines): calibrate module size.
- Format information: error correction level and mask.
- Data + error correction: the actual information encoded with redundancy.
Error correction: why they work even when scratched
QR codes use Reed–Solomon to add redundancy. Four levels:
| Level | Recovery | Typical use |
|---|---|---|
| L (Low) | ~7% | Little damage risk |
| M (Medium) | ~15% | Standard, good balance |
| Q (Quartile) | ~25% | Advertising, stickers |
| H (High) | ~30% | Industrial, dirty environments |
The more correction, the less data capacity for the same size. Our generator uses M by default.
Static vs. dynamic QRs
| Static | Dynamic |
|---|---|
| Data embedded directly | Short URL that redirects |
| Never expires, cannot be changed | Destination changes without reprinting |
| Free, no server | Requires a redirection service |
| Private (only you hold the data) | Provider sees the statistics |
Versions (size)
QR codes go from version 1 (21×21 modules) to version 40 (177×177). The more data, the higher the version. A short URL fits in v1–v3; a full vCard needs v10+.
Common uses today
- Menus and cards in hospitality (post-COVID).
- Tickets and boarding passes (planes, trains, events).
- Payments (Bizum, PayPal, banking codes).
- 2FA authentication (scan a QR to add TOTP in apps).
- Marketing (flyers, packaging, business cards).
- Logistics and traceability (its original use).
Generate your QR codes for free
Our QR code generator creates static QRs downloadable as SVG (vector, infinite print quality). Enter your text or URL, choose the error correction level and download. Everything happens in your browser: your data is never sent to any server.
Conclusion
A QR code is a compact, robust and universally readable data container. Understanding its parts (version, correction, type) lets you use them with confidence: for your Wi-Fi, your website, your contacts or your event. Generate yours, test them and use them without limits.