Every QR code term, explained

How QR codes and barcodes work, what each part is for, which formats carry payments, contacts and Wi-Fi logins, and how to print a code that scans. Plain English, with the standards behind it.

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QR codeA QR code is a two-dimensional matrix barcode that stores data in a square grid of dark and light modules. DENSO WAVE invented it in 1994, and phone cameras and imaging scanners can read it.Read
Static vs dynamic QR codeA static QR code encodes its final data directly, so it cannot change. A dynamic QR code encodes a short redirect link, so the destination can be edited and scans can be counted.Read
Error correction levelsError correction levels set how much of a QR code can be damaged and still scan. There are four: L recovers about 7% of codewords, M about 15%, Q about 25% and H about 30%.Read
Quiet zoneThe quiet zone is the blank margin around a QR code. The standard asks for four modules of clear space on every side, two for Micro QR, so a scanner can tell where the code begins.Read
Minimum print size and scan distanceA QR code’s minimum size depends on scan distance and module count. A common rule of thumb is a code width of one tenth of the scan distance, and about 2 cm (0.8 in) as a floor for short URLs.Read
Wi-Fi QR codeA Wi-Fi QR code stores a network name, password and security type so a phone can join the network by scanning, with no typing. Its text looks like WIFI:T:WPA;S:MyNetwork;P:secret;;.Read
Quishing (QR phishing)Quishing is phishing through a QR code: a scammer uses a code to send people to a fake website that steals passwords, payment details or personal information, or that installs unwanted software.Read
Data MatrixA Data Matrix is a square or rectangular 2D barcode with a solid L-shaped border on two sides and a dotted clock track on the other two. It is defined in ISO/IEC 16022.Read

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Basics

What a QR code is, how it works, where it came from, and how it compares with links, NFC and apps.

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Anatomy

The parts of a QR code: modules, finder and alignment patterns, the quiet zone, versions and masks.

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Encoding

How data becomes modules: encoding modes, character sets, and the error correction that survives damage.

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2D symbologies

The other two-dimensional codes: Micro QR, rMQR, Data Matrix, Aztec, PDF417, MaxiCode and more.

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Barcodes and GS1

Linear barcodes on retail goods and cartons, GTINs, and the move to 2D codes at checkout.

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Payment codes

The QR payment formats used around the world, from EMV and national schemes to bank transfers and crypto.

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What a code can hold

The payload formats behind contact cards, Wi-Fi logins, locations, calendar events, tickets and more.

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Standards

The ISO/IEC and JIS documents that define how each symbology is built and read.