Accessibility glossary

The Accessible Canada Act (2019) — Canada's federal accessibility law. Applies to entities under federal jurisdiction (banking, telecom, broadcasting, federal government). Standards are set by the Accessibility Commissioner.

Microsoft's free open-source accessibility testing tool — both an automated checker (axe-core under the hood) and a guided manual-test framework that walks auditors through structured assessments.

A third-party JavaScript widget that injects automated "fixes" into a page after it loads — typically a sidebar with profile presets (high contrast, larger text, etc). Independent audits consistently find overlays add new barriers faster than they remove existing ones.

A public-facing document declaring an organisation's accessibility commitments, target conformance level, known gaps, and how to report barriers. Required by EAA Article 7, PSBAR, and most public-sector regimes.

The internal data structure browsers and operating systems build from the DOM, mapping every element to a role, name, state, and relationships — the data screen readers and other assistive technology actually traverse.

The Americans with Disabilities Act, the foundational US disability-rights law (1990). Title III, which covers public accommodations, has been the primary basis for web accessibility lawsuits in US federal court.

The text alternative for non-text content. Screen readers announce alt text in place of the image; if the image fails to load, sighted users see it. Purely decorative images get `alt=""`, not omitted.

The Accessibility for Ontarians with Disabilities Act (2005) — Ontario's accessibility regime, applying to organisations with 50+ employees. Web content must conform to WCAG 2.0 Level AA.

Accessible Rich Internet Applications — a W3C specification that defines roles, states, and properties for making custom UI controls accessible to assistive technology.

The W3C's pattern library for accessible custom widgets. The APG is the operative how-to companion to the ARIA spec — it shows what ARIA looks like when used correctly.

Authoring Tool Accessibility Guidelines — WCAG's sibling standard for tools that *create* web content (CMSes, design tools, IDEs). ATAG specifies that authoring tools must both be accessible and help authors create accessible output.

A narrated description of visual content in a video — actions, scene changes, text on screen, expressions — for blind viewers. WCAG 1.2.3 (AA) and 1.2.5 (AA pre-recorded extended) require it.

An open-source automated accessibility testing engine from Deque, used by browser extensions (axe DevTools, Accessibility Insights), CI scripts, and Lighthouse. Catches an estimated 30–40% of WCAG issues.

Germany's accessibility statutory stack — the BFG (federal disability-equality law), BITV (web/IT accessibility regulation), and BFSG (the EAA implementation in Germany).

Text representation of all meaningful audio in video — dialogue plus speaker identification, sound effects, and music cues. WCAG 1.2.2 requires captions for pre-recorded video. Distinct from subtitles.

Accessibility for users with cognitive, learning, and neurological disabilities — working-memory limitations, attention disorders, dyslexia, dyscalculia, autism, intellectual disability, brain injury, and dementia. The under-served dimension of WCAG.

The umbrella term for genetic or acquired conditions that affect colour perception. Affects roughly 8% of men and 0.5% of women globally. WCAG 1.4.1 prohibits colour as the sole means of conveying information.

WCAG's tiered grading: **A** (minimum), **AA** (broadly required), **AAA** (highest). Each criterion is assigned exactly one level. Most laws and contracts target Level AA.

The luminance ratio between foreground text and its background, on a scale from 1:1 to 21:1. WCAG 2.x requires 4.5:1 for normal text and 3:1 for large text (≥18pt or 14pt bold) at Level AA.

The UN Convention on the Rights of Persons with Disabilities (2006). The international human-rights treaty that 180+ countries have ratified; the framing every regional accessibility law traces back to.

The European Accessibility Act (Directive 2019/882) — the EU law that, from June 28 2025, requires accessibility for a wide range of consumer products and services across all member states. Covers e-commerce, banking, transport, e-books, and more.

The European accessibility standard that EU procurement law and the European Accessibility Act cite. EN 301 549 wraps WCAG 2.1 AA and extends it with mobile + hardware requirements.

The W3C specification (now ISO/IEC 23761) that defines accessibility metadata and conformance for EPUB digital publications. Mandated for in-scope e-books under the European Accessibility Act.

The UK's primary anti-discrimination law. Section 20 (reasonable adjustments) and Schedule 2 apply to service providers — including websites — operating in the UK.

The currently-active element receiving keyboard input. WCAG requires a visible focus indicator (2.4.7) and that focus order is logical (2.4.3). Tab and Shift+Tab move focus through interactive elements.

The pattern that keeps keyboard focus inside a modal dialog while it's open — preventing Tab from escaping back to the document underneath, and restoring focus to the trigger element when the dialog closes.

The CSS media query that detects user-configured high-contrast modes — primarily Windows High Contrast Mode, plus Chrome / Edge Forced Colors. Authors use it to adapt rendering when system colour preferences override site styles.

The structural use of `<h1>` through `<h6>` to convey content organisation. Screen-reader users navigate by heading; an incoherent hierarchy makes a page incoherent for them. WCAG 1.3.1 requires programmatic heading structure.

The design philosophy that treats disability as a mismatch between people and their environment, designing for the widest range of human diversity by intentionally including disabled users and edge cases as core users.

Job Access With Speech — a commercial Windows screen reader from Freedom Scientific. The historical market leader in enterprise screen-reader use; commonly paired with Chrome or Edge.

All functionality must be operable without a mouse. Tab moves between focusable elements; Enter/Space activates; arrow keys navigate within widgets. Users who rely on switch input, voice control, or a screen reader are all routed through the keyboard interface.

A region of a page identified by HTML5 element or ARIA role that screen-reader users can navigate to directly. Landmarks (banner, navigation, main, complementary, contentinfo) form the page's structural skeleton.

Google's open-source web-quality auditor, bundled with Chrome DevTools and the PageSpeed Insights API. Its accessibility audit wraps axe-core's rule set. Scores 0–100, but a score of 100 doesn't mean WCAG-compliant.

An ARIA-managed region that announces dynamic content updates to screen readers without moving focus. The `aria-live` attribute makes a section of the DOM `polite` or `assertive` for accessibility-tree notifications.

NonVisual Desktop Access — a free, open-source Windows screen reader from NV Access. The most-tested screen reader by web developers; close to JAWS in market share.

An open-source command-line accessibility tester. The CI-friendly companion to axe-core CLI; pa11y-ci powers the nightly site-wide accessibility regression workflows most large accessibility programmes adopt.

ISO 14289 — the international standard for accessible PDF documents. Cited by EAA, Section 508, and EN 301 549 chapter 10 as the conformance target for PDF accessibility.

The writing practice that produces clear, concise content readable by the broadest possible audience — supporting cognitive accessibility, low-literacy users, and non-native speakers. Cited by the US Plain Writing Act, ISO 24495, and many EU accessibility regimes.

The four principles WCAG is built on: **Perceivable, Operable, Understandable, Robust.** Every success criterion maps to one of these.

The UK Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018 — the UK's transposition of the EU Web Accessibility Directive. Retained as UK law post-Brexit.

A commercial accessibility platform that closes the loop between detection and remediation — continuous scanning, an IDE code assistant, Accessibility Statement and VPAT generators, and an MCP server so AI agents can drive the workflow directly.

The user preference for reduced or eliminated motion, exposed to authors via the `prefers-reduced-motion` CSS media query. WCAG 2.3.3 (AAA) requires that motion can be disabled.

A hardware device that converts on-screen text into refreshable braille on a row of pins, paired with a screen reader. The braille-first interface to digital content for braille-fluent blind users.

Référentiel général d'amélioration de l'accessibilité — France's national accessibility standard and audit reference. Maintained by DINUM; the operative checklist behind France's WAD and EAA implementations.

Assistive technology that enlarges a portion of the screen for low-vision users. Most major OSes ship one (Windows Magnifier, macOS Zoom); commercial products (ZoomText, MAGic) add features like custom contrast palettes and document tracking.

Software that converts on-screen content into synthesized speech or refreshable braille. The dominant desktop screen readers are JAWS (paid, Windows), NVDA (open-source, Windows), and VoiceOver (built into macOS/iOS). TalkBack is the Android counterpart.

A US federal procurement requirement (29 U.S.C. § 794d): federal agencies can only buy ICT — websites, software, hardware — that conforms to accessibility standards. The current standard (2018 Refresh) wraps WCAG 2.0 AA.

Using HTML elements for their meaning, not just their default appearance. A `<button>` announces as a button; a `<div onclick>` announces as nothing. The vast majority of accessibility failures trace back to abandoned semantics.

A keyboard shortcut at the very top of every page that lets users jump past repeated navigation to the main content. Required for WCAG 2.4.1 Bypass Blocks.

A category of assistive technology that lets users with significant motor disability operate a computer by activating one or more physical switches. The strict cousin of keyboard accessibility — any switch user is also a keyboard user.

Google's built-in Android screen reader. The mobile counterpart to NVDA / VoiceOver. Pairs with Chrome by default.

The minimum size of interactive elements activated by pointer input. WCAG 2.5.5 (AAA) requires 44×44 CSS pixels; WCAG 2.5.8 (AA, new in 2.2) requires 24×24. Critical for users with motor disabilities and small-screen users generally.

The class of assistive technology that lets users operate a computer through spoken commands. Dragon NaturallySpeaking (Windows), macOS / iOS Voice Control, Windows Speech Recognition — all rely on accessible names matching the spoken command.

Apple's built-in screen reader, included on every macOS and iOS device. On iOS, VoiceOver is the assumed reference screen reader for mobile-web accessibility testing.

Voluntary Product Accessibility Template — a vendor's self-declaration of how a product conforms to accessibility standards (Section 508, EN 301 549, WCAG). The current template is VPAT 2.5 (Revised Section 508 + EN 301 549 + WCAG 2.x).

The W3C's emerging vocabulary for personalisation semantics — letting users adapt content to their cognitive, sensory, and motor preferences through declarative metadata rather than user-customised CSS.

WebAIM's free browser-extension accessibility evaluation tool. The visual companion to axe-core's CI-friendly checker — WAVE overlays accessibility findings directly on the rendered page.

The Web Content Accessibility Guidelines, the W3C standard most accessibility laws cite. WCAG defines what makes web content perceivable, operable, understandable, and robust for people with disabilities.

The current published version of WCAG (October 2023). Adds nine new success criteria over WCAG 2.1, mostly around focus visibility, drag operations, and accessible authentication.

The next major version of WCAG, currently in working-draft. Replaces the pass/fail success-criteria model with a scoring system across multiple guidelines.

Directive (EU) 2016/2102 — the EU law that, since September 2018, requires public-sector websites and mobile apps across all 27 member states to be accessible. The EAA's public-sector predecessor.