Files and data
What is QR code?
Short for Quick Response code.
A QR code is a square two-dimensional barcode that stores text, a web address or other data in a grid of dark and light modules.
How it works
A scanner locates the three large squares in the corners, works out the grid’s size and angle, then reads each module as a one or a zero. Built-in error correction means the code can still be read when part of it is damaged or covered, which is how logos in the middle of codes work.
A clear border around the code, called the quiet zone, helps scanners find it. More data generally requires a denser grid, so short links make codes that are easier to scan from a distance.
QR codes can store plain text, web addresses, Wi-Fi network details, contact cards, email and SMS templates. Phones recognize these payload types and offer the matching action, such as joining the network or saving the contact.
A practical example
A QR code can contain a website address or Wi-Fi connection details. Scanning a URL code shows the encoded address before you decide whether to visit it.
What to watch out for
The code itself doesn’t establish that a destination is trustworthy. Check the decoded address, and test the final printed or resized code before distributing it.
Tools you can use
- QR Code Generator · Static codes that never expire, checked before download
- QR Code Scanner · See where a code leads before you open it
Go a little deeper
- Do QR codes expire?
- How to make a QR code for a link
- How to put a QR code on a business card
- How to scan a QR code from a screenshot
Common questions
Do QR codes expire?
A static QR code stores its data directly and works forever. Dynamic codes from some services point to a redirect link, which stops working if the subscription ends.
How small can a QR code be printed?
About 2 × 2 cm is a practical minimum for a short link scanned at arm’s length. Longer data makes a denser grid that needs to be printed larger.
Why won’t my QR code scan?
The usual causes are too little contrast, a missing quiet zone, blurring from enlarging a small image, or a design that covers too many modules. Export as SVG or a large PNG for print.