QR Code Glossary
Key terms and definitions in QR code technology, organized by topic.
QR Code Structure
Module
The smallest square unit (dark or light) in a QR code.
Finder Pattern
Three corner squares that enable scanner orientation.
Alignment Pattern
5x5 reference squares correcting for image distortion.
Timing Pattern
Alternating black/white lines defining the module grid.
Quiet Zone
Required 4-module white margin around the QR code.
Format Information
15-bit field storing EC level and mask pattern.
Version Information
18-bit version identifier for QR codes version 7+.
Dark Module
Single always-black module used as a reference point.
Data Region
The area carrying encoded data and error correction.
Separator
White border isolating finder patterns from data.
Version
Size designation (1-40) determining module count.
Module Size
Physical dimension of one module (min 0.33mm).
Mask Pattern
One of 8 XOR patterns optimising module distribution.
Penalty Score
Score evaluating mask quality via four penalty rules.
Remainder Bits
Zero-padding filling remaining modules after EC data.
Error Correction
Error Correction Level
L/M/Q/H levels defining 7-30% damage recovery.
Reed-Solomon Code
Symbol-level error correction code used in QR data.
Codeword
8-bit data unit in the QR code data stream.
Interleaving
Distributing codewords across blocks for damage resistance.
BCH Code
Error correction protecting the format information field.
Golay Code
Error correction for the version information field.
Galois Field
GF(256) finite field used in Reed-Solomon arithmetic.
Generator Polynomial
Polynomial generating Reed-Solomon EC codewords.
Error Correction Capacity
Maximum correctable symbol errors per block.
Data Capacity
Maximum characters per version, EC level, and mode.
Encoding & Data
Encoding Mode
Data encoding method (numeric/alphanumeric/byte/kanji).
Numeric Mode
Digits only at 3.33 bits/char — most efficient mode.
Alphanumeric Mode
45-character set at 5.5 bits/char — uppercase only.
Byte Mode
Any byte at 8 bits/char — default for most content.
Kanji Mode
Japanese characters at 13 bits/char via Shift JIS.
ECI Mode
Meta-mode switching character encoding (e.g., to UTF-8).
Mode Indicator
4-bit prefix identifying the data encoding mode.
Character Count Indicator
Bit field specifying the data segment length.
Terminator
0000 sequence marking the end of encoded data.
Padding Codeword
Filler bytes (0xEC/0x11) completing data capacity.
Structured Append
Split one message across up to 16 QR symbols.
FNC1 Mode
Mode for GS1 barcodes and AIM application data.
Standards & Specifications
ISO/IEC 18004
The international QR code standard (ISO).
JIS X 0510
The original Japanese QR code standard (JISC).
GS1 Digital Link
GS1 standard for product IDs as web URIs in QR codes.
EMV QR Code
EMVCo payment QR code specification.
BIP 21
Bitcoin URI standard for payment QR codes.
Micro QR Code
Compact QR variant with one finder pattern (M1-M4).
Rectangular Micro QR (rMQR)
Rectangular QR variant for narrow printing areas.
SQRC
Secure QR with encrypted private data layer (DENSO WAVE).
Shift JIS
Japanese character encoding for QR Kanji mode.
ISO 8859-1
Default byte mode encoding (Latin-1, 256 characters).
Scanning & Reading
QR Code Scanner
Device or app that reads and decodes QR codes.
Decoding
The full process of extracting data from a QR image.
Scan Distance
Maximum reading distance (approx. width / 10).
Camera Resolution
Camera pixel count affecting minimum scannable QR size.
Orientation
QR codes read from any rotation via finder patterns.
Distortion Correction
Compensating for perspective and curvature in scanning.
Print Resolution
DPI for printing — minimum 300 DPI recommended.
Contrast Ratio
Dark/light module brightness difference (min 37.5%).
Scan Failure
Failed QR decode — common causes and prevention.
Zigzag Pattern
Two-module-wide up/down reading order for data.
Binarisation
Converting grayscale QR image to black/white pixels.
Coordinate System
Row/column grid identifying module positions.
Visual Design
Custom QR Code
Branded QR code with colours, logos, or artistic elements.
Logo Integration
Centre logo placement using EC to recover obscured data.
Colour QR Code
QR code with brand colours maintaining contrast.
Rounded Modules
Circular or rounded module shapes for softer appearance.
SVG QR Code
Vector format QR for infinite-resolution scaling.
Inverted QR Code
White-on-dark colour reversal (reduced compatibility).
Gradient QR Code
Colour gradient across modules — risky for scanning.
Frame QR Code
QR variant with dedicated centre canvas area (iQR).
Artistic QR Code
QR codes integrated into artwork or illustrations.
Call to Action (CTA)
Text prompt near QR code instructing users to scan.
Security & Privacy
QRishing
QR code phishing — fraudulent codes directing to malicious sites.
QR Sticker Attack
Malicious sticker overlaid on legitimate QR code.
URL Preview
Scanner feature showing URL before opening.
Tamper-Evident QR
QR on tamper-evident materials showing removal damage.
Cryptographic Signature
Digital signature verifying QR code authenticity.
EU Digital COVID Certificate
EU digitally signed health QR certificate standard.
Data Privacy
Privacy risks of personal data in scannable QR codes.
QR Code Malware
Malicious URLs or exploit payloads in QR codes.
TOTP QR Code
otpauth:// URI QR for 2FA authenticator setup.
Watermarking
Invisible tracking data embedded in QR module patterns.
Dynamic QR
Dynamic QR Code
Redirect-based QR with changeable destination.
Static QR Code
Fixed-content QR with no server dependency.
URL Redirect
Server-side HTTP redirect powering dynamic QR codes.
QR Analytics
Scan tracking: count, location, device, and timing.
Short URL
Compact URL minimising QR code size.
QR Code Expiration
Time or scan-limited dynamic QR code validity.
A/B Testing QR
Split-testing destinations via dynamic QR redirect.
Geotargeted QR
Location-based destination routing via dynamic QR.
Device-Targeted QR
OS-based routing (iOS to App Store, Android to Play).
Batch QR Generation
Programmatic creation of many unique QR codes.
Industry Applications
Contactless Menu
Digital restaurant menu via table-top QR code.
Mobile Boarding Pass
IATA BCBP QR code on smartphone for flight boarding.
UDI (Unique Device Identification)
FDA-mandated medical device QR identification.
GTIN
GS1 product identifier encoded in QR via Digital Link.
QR Code Payment
Financial transactions via merchant/consumer QR codes.
QR Code Coupon
QR-delivered discount codes and promotional offers.
Digital Business Card
vCard/MeCard QR on business cards for instant contacts.
vCard
RFC 6350 electronic contact format for QR codes.
MeCard
Compact NTT DoCoMo contact format for small QR codes.
WiFi QR Code
QR encoding WiFi credentials for auto-connection.
Supply Chain QR
QR tracking from manufacturer to consumer.
MPM (Merchant-Presented Mode)
Merchant displays QR, customer scans to pay.
CPM (Consumer-Presented Mode)
Consumer shows QR, merchant scans to accept payment.
iCalendar QR
QR-encoded calendar event (RFC 5545 iCalendar).
Geo URI QR
QR-encoded GPS coordinates opening maps app.
History & Innovation
DENSO WAVE
Japanese inventor of QR codes (1994, Toyota Group).
Masahiro Hara
Lead inventor of the QR code at DENSO WAVE.
1994 Invention
QR code creation year — DENSO WAVE for Toyota.
Quick Response
'QR' = Quick Response, for high-speed assembly scanning.
Open Standard
DENSO WAVE's free patent licensing enabling global adoption.
Data Matrix
Competing 2D barcode (ISO 16022) without finder patterns.
Aztec Code
2D barcode with bulls-eye centre, used for boarding passes.
2D Barcode
Barcode encoding data in two dimensions (QR, Data Matrix).
1D Barcode
Traditional linear barcode (UPC/EAN) — predecessor to QR.
CBOR
Compact binary data format for QR credentials (RFC 8949).
UTF-8
Unicode encoding via ECI 26 for multilingual QR data.
Smartphone QR Adoption
Native camera QR scanning in iOS 11 / Android 9.
Frequently Asked Questions
What QR code terms are defined in the glossary?
The glossary covers technical terms including version, module, quiet zone, error correction level, finder pattern, mask pattern, and encoding mode.
What is error correction in a QR code?
Error correction allows a QR code to be decoded even when partially damaged. Levels L, M, Q, and H restore 7%, 15%, 25%, and 30% of data respectively.
What is a QR code module?
A module is the smallest unit (square dot) in a QR code. A Version 1 QR code has a 21×21 module grid; each additional version adds 4 modules per side.
What is the quiet zone in a QR code?
The quiet zone is the mandatory blank border of at least 4 modules surrounding the QR code that ensures scanners can locate and isolate the symbol.