QR code definition

QR (Quick Response) codes are two-dimensional barcode-like images used to convey binary/digital information visually, often in print, allowing readers (basically computers with cameras) to quickly read text and large numbers. They can also be used by many devices (such as smart phones) to quickly share such information, often by using a program (or "app") that displays it in a QR code for another reader. They usually can be identified by users easily by their distinctive patterns, labels or markers. Their main advantage is to help share information with users without them having to type it out themselves, which can also reduce errors or "typos". QR codes were invented in 1994 by Japanese company "Denso Wave", but didn't become commonplace globally until the 2010's.

Most QR codes are purely black and white and squared or rectangular, consisting of seemingly-random square "dots" or pixels, often with three squared bullseye-like patterns in the corners. With an optical imaging device, a reader can process an image until it finds enough contrasting blacks-and-whites and seeks certain patterns before attempting to measure, decode and error-correct. Although it's possible for human to interpret some QR codes, it's often extremely difficult and always inefficient, so for public information the code may have the human-readable version of the info nearby. QR codes can make it quick and easy to share private messages between smartphones or desktops-to-smartphones, as onlookers can't read the encoded message, however any image captured of their screens (by another reader or a photograph or video) may allow them to do so, unless the embedded message was encrypted. Nonetheless it's still not recommended to share sensitive data this way.

Common uses of QR codes include: item tagging, user or app identifying, phone number and website link (URL) sharing, connecting Wi-Fi hotspots and payment or token transactions.