QR codes — Computing, 7–10
A QR code is a pattern that stores small pieces of information so a camera can read them quickly.
A pattern with a message
A QR code looks like a square made from dark and light patches. Those patches are arranged so a camera can turn the pattern into information, such as a website address, a ticket number or a short message. The code does not understand the message; it only provides a compact way to represent it.
Why make information scannable?
Typing a long web address or ticket number on a small phone is slow and can cause mistakes. QR codes were developed to let machines read information quickly, even when the code is printed on a box or sign. Their square layout also includes clues that help the reader find the code and cope with some dirt or damage.
Scanning a lunch-menu code
A café puts a QR code beside its lunch menu. First, you open the camera and point it at the whole square. The camera recognises the corner markers, reads the dark-and-light pattern and reconstructs the stored web address. You tap the notice, and the browser opens that address; the code itself did not open anything by magic.
A scan is not a safety check
Because a QR code looks official and is easy to scan, you may trust it without checking. But anyone can print a new code over an old one, and the code may lead to a misleading or unsafe website. Before tapping, check the address shown and stop if it asks for a secret, a payment or something that feels wrong.
Codes on real things
You can find QR codes on museum labels, transport tickets, food packaging, posters and library books. They connect a physical object to extra digital information without printing a whole page beside it. They are useful when the message is short or points somewhere online, but they are not a good replacement for clear printed instructions in every situation.
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