QR codes, explained
What is a QR code?
A QR code (short for Quick Response code) is a square, two‑dimensional barcode that a phone camera can read in a fraction of a second. Unlike a classic barcode, which stores a short number in a single row of lines, a QR code stores information both horizontally and vertically. That lets it hold a full web address, a message, contact details or Wi‑Fi credentials in a small printed square.
QR codes were invented in 1994 by Denso Wave, a Japanese company, to track car parts in factories. They became an everyday tool once smartphone cameras started reading them without a separate app. Today you’ll find them on restaurant menus, posters, packaging, business cards, tickets and shop windows.
How does a QR code work?
A QR code is a grid of black and white squares called modules. The three large squares in the corners are finder patterns: they tell a camera where the code is and which way up it is, so it can be scanned from any angle. Smaller patterns inside the code help the camera correct for distance and perspective.
The rest of the grid holds your content, plus extra error correction data. Error correction is what lets a slightly scratched, smudged or partly covered code still scan. This generator uses a high level of error correction, so a code can lose part of its surface and keep working.
Static and dynamic QR codes
A static QR code stores your content directly in the pattern. It needs no server, no account and no subscription, and it never expires. The trade‑off: once printed, its content can’t change. To point it somewhere else, you make and print a new code.
A dynamic QR code stores a short web address that forwards to your destination. Because the forwarding happens online, you can change where the code leads after it’s printed and see how many people scan it. Dynamic codes depend on the service that hosts them, which is why they usually cost money.
What can a QR code contain?
- Website links: menus, online shops, booking pages, portfolios, social profiles, videos and documents.
- Plain text: instructions, serial numbers, short notes or codes.
- Email: opens a new email to your address, ready to send.
- Phone numbers: starts a call in one tap.
- Wi‑Fi details: lets guests join your network without typing a password.
How to make a QR code that always scans
- Size it right. Print it at least 2 × 2 cm (about 0.8 × 0.8 in). For codes read from further away, a useful rule is that the scanning distance can be about ten times the width of the code.
- Keep the contrast high. Use a dark code on a light background. Light codes on dark backgrounds, or colours that are too similar, often fail to scan.
- Leave a margin. The empty border around a code, called the quiet zone, helps cameras find it. Our downloads include it automatically.
- Keep content short. Shorter content makes a simpler pattern that scans faster and from further away.
- Use SVG for print. SVG files stay perfectly sharp at any size, from a sticker to a billboard.
- Test before you print. Scan your code with a couple of different phones, in the light where it will be used.
How to scan a QR code
On most iPhones and Android phones, open the camera and point it at the code. A link or action appears on screen; tap it to open. If nothing happens, check that QR scanning is turned on in your camera settings, or use the scanner in Google Lens.