QR Code Glossary — Complete Terms & Definitions

Quick Response Code. A two-dimensional matrix barcode that stores data as a pattern of black and white squares. First developed in 1994 by Denso Wave in Japan for tracking automotive parts. Modern QR codes comply with ISO/IEC 18004:2015 and can encode URLs, text, contact information, WiFi credentials, and more. When a smartphone camera focuses on a QR code, the device automatically decodes the data and takes the appropriate action (opening a URL, saving a contact, connecting to WiFi).

A QR code in which the destination URL or content is permanently encoded in the QR pattern itself. Once generated, the content cannot be changed — a new QR code must be generated for a different destination. Static QR codes never expire, require no server infrastructure, and need no account or subscription. They are the most common type of QR code. All QR codes generated by UnlimitedQRCodes.com are static codes.

A QR code that encodes a short redirect URL pointing to a server-side redirect table. The destination URL can be changed after the physical code is printed, without regenerating or reprinting the code. Dynamic QR codes typically include scan analytics (scan count, location, device). They require a paid subscription and server infrastructure from the QR generator. Dynamic QR codes are offered by QR Tiger, Bitly, and others — typically from $5–$10/month. UnlimitedQRCodes.com generates static codes only.

The international standard that defines QR code specification — covering the symbol structure, data encoding, error correction, scanning parameters, and printing requirements. First published in 2000 and updated in 2015 (ISO/IEC 18004:2015). Any QR code generator that complies with this standard produces codes that are compatible with all ISO-compliant scanners, including smartphone camera apps on iOS and Android. UnlimitedQRCodes.com generates QR codes compliant with ISO/IEC 18004:2015.

A setting that determines how much of the QR code data can be restored if the code is physically damaged or partially obscured. Four levels: L (Low) — 7% data recovery, smallest code, easiest to scan; M (Medium) — 15% data recovery, balance of size and resilience; Q (Quartile) — 25% data recovery, used when some damage is expected; H (High) — 30% data recovery, most resilient, larger code, required for logo embedding. Higher error correction levels produce larger, denser QR codes. Most QR generators auto-select M for standard use.

The individual square dots that make up a QR code pattern. A QR code consists of a grid of modules — black modules encode data bits, white modules are background. The size of a QR code version (1 through 40) determines the number of modules: Version 1 is 21×21 modules, Version 40 is 177×177 modules. More modules = more data capacity. The physical size of a printed module determines the minimum printable size of the QR code for reliable scanning.

The three square patterns in the corners of a QR code (top-left, top-right, bottom-left). Each consists of a 7×7 module black square, surrounded by a white border, surrounded by a black border. The finder patterns allow QR scanner algorithms to locate and orient the QR code regardless of rotation or angle. The bottom-right corner has no finder pattern — it is occupied by data modules and alignment patterns (in Version 2+ codes). Clipping or damaging a finder pattern typically makes the QR code unscannable.

The white border that must surround a QR code on all four sides to allow scanners to identify where the code begins and ends. The minimum quiet zone width is 4 modules (the same unit as the QR code's internal modules). Placing a QR code flush to the edge of a design — with no white margin — typically causes scan failures. Always leave a quiet zone of at least 4mm around a printed QR code.

An open standard file format for electronic business cards, defined in RFC 2426 (vCard 3.0) and RFC 6350 (vCard 4.0). A vCard file encodes contact information — name, phone, email, organisation, title, website, address — in a structured text format. When a vCard QR code is scanned by a smartphone, the device reads the vCard data and prompts the user to save the contact to their address book. vCard 3.0 is the most universally compatible version — supported by all modern smartphones natively without a third-party app.

Service Set Identifier. The name of a WiFi network as it appears when devices search for available networks. An SSID is a string of up to 32 characters (letters, numbers, and symbols). For WiFi QR codes, the SSID must be entered exactly as it appears in the network name field — capitalisation and spaces matter. Example: 'CaféGuestWiFi' and 'cafeguestwifi' are different SSIDs.

Wi-Fi Protected Access 2 and 3 — the current security protocols used by most WiFi routers. WPA2 (introduced 2004) is the dominant standard for home and business routers worldwide. WPA3 (introduced 2018) offers improved security and is standard on routers manufactured from 2019 onwards. For WiFi QR codes, select WPA/WPA2 for most networks and WPA3 only if you know your router specifically uses WPA3. The older WEP protocol should be avoided — it is insecure and rarely encountered. Open networks (no password) select 'None'.

A QR code that encodes WiFi network credentials in the WiFi QR code format: WIFI:T:[security];S:[SSID];P:[password];;. When scanned by a modern smartphone, the phone automatically prompts the user to join the encoded network without typing credentials. Supported natively on iPhone (iOS 11+, which covers iPhone 7 and newer) and Android phones (Android 10+). For pre-Android-10 devices, a QR scanner app may be needed. Used by restaurants, hotels, offices, and homes to share guest WiFi without printing passwords or staff interruption.

An XML-based vector image format that describes graphics as mathematical shapes rather than pixels. SVG files can be scaled to any size — from a 1.5cm business card QR code to a 2-metre outdoor billboard — without any quality loss or pixelation. SVG is the required format for professional QR code print production. Send SVG files to print shops, packaging suppliers, and graphic designers. Never use JPEG or low-resolution PNG for QR code print production.

A raster (pixel-based) image format that uses lossless compression. PNG preserves the exact pixel values of the QR code without introducing compression artifacts that could degrade module edges and cause scan failures. QR codes from UnlimitedQRCodes.com download as 1000×1000 pixel PNG files. PNG is appropriate for: digital display (websites, emails, presentations, social media), screen-only use, and printing at small-to-medium sizes where the native pixel resolution is sufficient. For professional print production at any size, use SVG.

A QR code that encodes a web address (URL/URI). When scanned, the smartphone's browser opens the linked page automatically. URL QR codes must begin with https:// or http:// to be recognised as web links by most scanner apps. Short URLs produce smaller, sparser QR codes that scan more reliably at small print sizes — use URL shorteners or domain redirects for long URLs before generating the QR code.

Processing that occurs entirely within the user's web browser using JavaScript, with no data transmitted to any server. Client-side QR code generation means the encoding algorithm runs locally — your URLs, WiFi passwords, contact details, and text never leave your device. This is the approach used by UnlimitedQRCodes.com, enabling GDPR Article 25 (Privacy by Design) compliance by eliminating data collection entirely. The opposite is server-side processing, used by most QR generators, where your data is transmitted to their servers for encoding.

General Data Protection Regulation — the EU's primary data privacy law (effective May 2018). UK GDPR is the retained domestic version post-Brexit. GDPR applies to any processing of personal data about EU/UK residents. Key requirements relevant to QR generators: Article 25 (Privacy by Design — minimise data collection by default), Article 5 (data minimisation principle — collect only what's necessary). Server-side QR generators that process user-entered URLs and contact details are data processors under GDPR and require Data Processing Agreements. Browser-side generators that collect zero data sidestep these obligations entirely.

A privacy engineering principle — and a legal requirement under GDPR Article 25 — that requires data protection to be built into systems from the ground up, not added as an afterthought. For QR code generators, Privacy by Design means: process data in the user's browser (not on servers), collect no data by default, make privacy the default state without user action. UnlimitedQRCodes.com implements Privacy by Design by performing all QR encoding client-side, maintaining no user database, and using no tracking cookies for QR generation.

California Consumer Privacy Act — California's state privacy law (effective January 2020), granting California residents rights over their personal information. Under CCPA, businesses that collect personal information must disclose what they collect, allow opt-out of data sale, and provide deletion rights. Businesses that do not collect personal information have no CCPA obligations. UnlimitedQRCodes.com collects zero personal information — all processing is in-browser — meaning no CCPA compliance obligations arise from QR generation activity.

The process of generating multiple QR codes simultaneously from a structured data source (typically a CSV spreadsheet). Each row in the CSV produces one QR code. The output is typically a labeled PDF grid (multiple codes per page) or a ZIP file of individual PNG/SVG images. Bulk generation is essential for businesses with multiple locations, large product catalogues, conference attendee lists, or hotel room WiFi networks. UnlimitedQRCodes.com offers free bulk generation of up to 30 codes per CSV batch with no account required — the only free tool with this capability.

The size designation of a QR code, from Version 1 (21×21 modules) to Version 40 (177×177 modules). Higher versions have more modules, higher data capacity, and produce denser, more complex QR patterns. Version selection is automatic — QR generators select the minimum version needed to encode the input data at the chosen error correction level. Short URLs produce Version 1–5 codes that scan reliably at very small sizes. Long URLs or vCard data with many fields produce higher-version codes requiring larger print sizes.