Glossary

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ACT Rules(also: Accessibility Conformance Testing Rules, ACT-R)

A set of standardized, machine-readable test rules developed by the W3C that provide specific, objective criteria for evaluating whether web content meets accessibility requirements like WCAG success criteria. ACT Rules aim to reduce inconsistency between different automated…

AChecker(also: IDI Web Accessibility Checker)

An open-source web accessibility evaluation tool that checks HTML content against accessibility standards including WCAG 2.0. AChecker identifies three types of issues: known problems (definite violations detectable by rule), likely problems (probable violations requiring human…

AI Coding Assistant(also: AI Pair Programmer, Code Copilot)

An artificial intelligence tool integrated into code editors that assists developers by generating code suggestions, completing code snippets, and answering programming questions using large language models trained on code repositories. In accessibility contexts, AI coding…

AODA(also: Accessibility for Ontarians with Disabilities Act)

Canadian provincial legislation enacted in 2005 that sets out a roadmap to make Ontario fully accessible by 2025. AODA establishes mandatory accessibility standards across five areas: customer service, information and communications, employment, transportation, and the design of…

ARIA Hidden(also: aria-hidden Attribute)

An WAI-ARIA attribute (aria-hidden="true") that removes an element and its descendants from the accessibility tree, making them invisible to screen readers and other assistive technologies while potentially remaining visually visible. ARIA hidden is used to suppress decorative…

ARIA Live Region(also: Live Region, ARIA Live)

An ARIA live region is a section of a web page marked with the aria-live attribute that announces dynamic content changes to assistive technologies without requiring user focus to move to the updated area. Live regions are essential for making real-time updates — such as status…

ARIA Live Region(also: Live Region, aria-live)

A section of a web page marked with the aria-live attribute that is dynamically updated and should be announced by assistive technologies when changes occur, even if the user's focus is elsewhere. Live regions have politeness levels: "polite" (announced at the next convenient…

ATK(also: Accessibility Toolkit, Linux Accessibility Toolkit, AT-SPI)

ATK (Accessibility Toolkit) is the accessibility framework for the Linux desktop environment, providing an API through which applications expose their user interface elements to assistive technologies such as the Orca screen reader. ATK defines interfaces for accessible objects…

Access Keys(also: Accesskeys, Keyboard Shortcuts)

Access keys are keyboard shortcuts defined in HTML using the accesskey attribute that allow users to activate or focus on specific elements — such as links or form controls — by pressing a key combination. Introduced as an accessibility feature to help keyboard-only users…

Access to Information(also: Information Access)

In the context of web accessibility, the concept that certain accessibility criteria are fundamentally about whether users can reach and perceive content at all, as distinct from criteria that improve the quality or experience of that access. Access to information serves as a…

AccessiWeb(also: AccessiWeb Reference List)

A French web accessibility methodology and reference list developed by BrailleNet, providing a practical application framework based on WCAG. AccessiWeb translates WCAG success criteria into testable criteria organized for use in conformance audits, quality assurance, and…

Accessibility API Mapping(also: AAM, Accessibility API Mappings, Acc API Mapping)

Accessibility API Mappings (AAMs) are W3C specifications that define how the semantics of web content technologies — such as HTML, SVG, and WAI-ARIA — correspond to features in platform accessibility APIs like MSAA/UIA on Windows, ATK/AT-SPI on Linux, and NSAccessibility on…

Accessibility Annotation(also: A-Annotation, Accessibility Metadata)

External metadata added to a web page to describe its visual layout structure, content groupings, and element roles for the purpose of improving accessibility without modifying the original page. Accessibility annotations typically identify visually distinct groups on a page,…

Accessibility Audit(also: Accessibility Review, A11y Audit)

A structured evaluation of a digital product, website, or application against established accessibility standards, typically WCAG, to identify barriers that prevent people with disabilities from using it effectively. An accessibility audit usually combines automated scanning…

Accessibility Barrier(also: A11y Barrier)

Any aspect of a digital product, web page, document, or service that prevents or impedes a person with a disability from perceiving, operating, understanding, or using it on an equivalent basis to someone without that disability. Examples include missing alt text on images,…

Accessibility Baseline(also: Baseline, Technology Baseline, WCAG Baseline)

An accessibility baseline, as used in WCAG 2.0 and later versions, is the set of technologies that a content author assumes are supported and enabled in the user agents (browsers and assistive technologies) used by their target audience. Authors must ensure that all content…

Accessibility Commons(also: AC Repository, AC Metadata Repository)

A shared metadata repository and schema proposed in 2008 by IBM, the University of Washington, Stony Brook University, and the University of Manchester to let accessibility-remediation research projects publish and reuse externally authored fixes for inaccessible web content. An…

Accessibility Conformance Level(also: WCAG Conformance Level, Conformance Level)

Accessibility conformance levels are the tiered ratings defined by the Web Content Accessibility Guidelines (WCAG) to indicate the degree to which web content meets accessibility success criteria. WCAG defines three levels: Level A (minimum, addressing the most critical…

Accessibility Conformance Testing(also: ACT, ACT Rules Format)

A W3C technical recommendation that defines a standardized format for writing rules to test web accessibility. The ACT Rules Format provides a consistent structure for describing what to test and what outcomes to expect, aiming to reduce inconsistency between different automated…

Accessibility Evaluation Method(also: AEM, Accessibility Testing Method)

A structured approach or procedure used to assess the accessibility of digital products, websites, or applications. Accessibility evaluation methods include conformance review (checking against standards like WCAG), barrier walkthrough (assessing barriers in context of specific…

Accessibility Gap(also: Usability Gap, Digital Divide)

The measurable disparity in task performance, user experience, or access between people with disabilities and people without disabilities when using digital technology. The accessibility gap is commonly measured through differences in task completion time, error rates, success…

Accessibility Metadata(also: A11y Metadata, Accessibility Annotations)

Structured information that describes the accessibility features, hazards, or access modes of digital content. Accessibility metadata can be embedded within content (such as alt text in HTML) or stored externally in separate databases or annotation systems. External…

Accessibility Metrics(also: Web Accessibility Metrics, Accessibility Scores, Accessibility Measurement)

Quantitative methods for measuring and scoring the accessibility level of websites or digital content. Accessibility metrics typically work by evaluating web pages against checkpoints derived from standards like WCAG, computing pass or failure rates, and then synthesizing these…

Accessibility Monitoring(also: Web Accessibility Monitoring, Accessibility Observatory)

Accessibility monitoring is the ongoing process of tracking and measuring the accessibility level of websites or digital products over time. Because web content is frequently updated, changes can inadvertently introduce new accessibility barriers or degrade previously achieved…

Accessibility Object Model(also: AOM)

The Accessibility Object Model (AOM) is a proposed W3C web standard that aims to give JavaScript developers direct programmatic access to the browser's accessibility tree. While WAI-ARIA allows authors to annotate HTML with accessibility semantics through markup attributes, the…

Accessibility Overlay(also: A11y Overlay, Accessibility Widget, Accessibility Plugin)

A third-party software product that applies a layer of JavaScript over a website claiming to automatically fix accessibility issues, typically through a toolbar widget offering features like text resizing, color contrast adjustment, and screen reader optimization. Despite…

Accessibility Policy(also: Web Accessibility Policy, Digital Accessibility Policy)

A formal organizational document that defines an institution's commitment to digital accessibility, typically specifying the standards to be followed (such as WCAG conformance levels), roles and responsibilities, timelines for compliance, and mechanisms for monitoring and…

Accessibility Progress Formula(also: APPF, Accessibility Progress Percentage)

A formula for quantitatively tracking progress in addressing accessibility issues on a website, expressed as APPF = A / ((A + B) + (T - C)), where A is the number of applicable checklist items that have been addressed, B is the number not yet addressed, T is the total number of…

Accessibility Retrofitting(also: Retrofitting, Accessibility Remediation)

The process of modifying existing products, websites, buildings, or systems after the fact to make them accessible to people with disabilities. Retrofitting is typically more expensive, time-consuming, and less elegant than designing for accessibility from the start, often…

Accessibility Violation(also: A11y Violation, Accessibility Error, Accessibility Issue)

Any instance where web content, code, or design fails to conform to established accessibility guidelines such as WCAG. Accessibility violations can be syntactic (missing required HTML elements or attributes), semantic (elements present but not meaningful), or layout-related…

Accessibility conformance(also: WCAG conformance, Accessibility compliance)

The degree to which a digital product meets the requirements of an accessibility standard such as WCAG, typically assessed at Level A, AA, or AAA. While conformance provides a measurable baseline for accessibility, it does not guarantee usability for all disabled users — a site…

Accessibility maturity model(also: Organizational accessibility maturity)

A framework for assessing how systematically an organization approaches digital accessibility, typically ranging from ad hoc or reactive practices to fully embedded, proactive processes. Maturity models help organizations identify gaps in their accessibility efforts — such as…

Accessibility overlay(also: Accessibility widget, Accessibility plugin, Overlay tool)

A software layer, typically implemented as a JavaScript widget or browser extension, that applies modifications to a website's presentation or behavior with the goal of improving accessibility. Overlays range from user-driven tools that empower individuals to fix specific…

Accessible Authentication(also: WCAG 3.3.7, Accessible Authentication (Minimum))

A web accessibility requirement introduced in WCAG 2.2 (Success Criterion 3.3.7) that mandates for each step in an authentication process relying on a cognitive function test — such as remembering a password, solving a puzzle, or transcribing distorted text — at least one…

Accessible Data Table(also: Accessible Table, Screen Reader-Friendly Table)

A data table designed and implemented to be effectively navigable and comprehensible by screen reader users. Accessible data tables require proper HTML markup including table headers (th elements), scope attributes to associate headers with data cells, captions describing the…

Accessible Name(also: Accessible Label, Acc Name)

The text string that assistive technologies such as screen readers use to identify and announce a user interface element. The accessible name is computed by browsers following the W3C's Accessible Name and Description Computation algorithm, which checks a priority-ordered…

Accessible Role(also: ARIA Role, Role)

An accessible role is a property that defines the type and expected behavior of a user interface element as exposed to assistive technologies through the accessibility tree. Roles communicate what an element is (e.g., button, link, heading, list, table, dialog) so that assistive…

Accessible Web Design(also: Accessible Web Authoring, Nonvisual Web Design)

Accessible web design refers both to the practice of designing webpages that meet accessibility standards (such as WCAG) and — in a second, increasingly important sense — to the practice of enabling people with disabilities to act as web designers themselves, not just as testers…

Accessmonkey

Accessmonkey was a 2007 client-side scripting framework, built on Greasemonkey for Mozilla Firefox, that let users and developers run site-specific JavaScript to repair inaccessible web pages on the fly. Scripts could add alternative text, restructure pages, or inject…

Accordion Interface(also: Accordion Widget, Collapsible Sections, Disclosure Widget)

A user interface pattern that presents content in vertically stacked sections, each with a header that can be expanded or collapsed to show or hide the associated content. Accordions are particularly useful for accessibility because they allow users to navigate a hierarchical…

ActionScript

A programming language used within Adobe Flash to create interactive content, animations, and web applications. ActionScript code was compiled into bytecode embedded in SWF files and executed by the Flash Player virtual machine. Because ActionScript ran inside the closed Flash…

Adaptive Navigation(also: Adaptive Navigation Support)

A technique in which a system dynamically modifies the presentation of navigational elements (such as links, menus, or breadcrumbs) based on user characteristics, behaviour, or context. In accessibility applications, adaptive navigation can reorder, annotate, hide, or highlight…

Adobe Flash(also: Flash Player, Flash, Macromedia Flash)

A discontinued multimedia software platform formerly used to create animations, rich internet applications, games, and video players embedded in web pages. Flash content was notoriously inaccessible to screen readers and other assistive technologies because the Flash Player…

Alt Text(also: Alternative Text, Alt Attribute, Image Description)

A textual description of an image that is embedded in the HTML code and read aloud by screen readers, providing blind and low vision users with information about visual content. Effective alt text is concise, descriptive, and context-appropriate — a decorative image may need…

Alt Text Authoring(also: Alt Text Writing, Image Description Authoring)

The process of composing alternative text descriptions for digital images, undertaken by content authors, developers, or dedicated accessibility specialists. Research has identified several barriers to effective alt text authoring, including authors not knowing what to include,…

Alternative Text(also: Alt Text, Alt Attribute)

Text associated with an image that serves the same purpose and conveys the same essential information as the image. Alternative text is a fundamental web accessibility requirement specified in WCAG, enabling screen reader users to understand image content. Standards for writing…

Anchor Text(also: Link Text, Hyperlink Text)

The visible, clickable text within a hypertext link that is intended to describe the link's destination or purpose. Descriptive anchor text (e.g., "download the annual report") provides clear information about what the user will find when they follow the link, while vague anchor…

Annotation-based Transcoding(also: Annotation-driven Transcoding, External Annotation)

Annotation-based transcoding is a web accessibility technique in which a third party (not the site owner) authors a separate metadata file — the 'annotation' — that describes how to restructure or re-label a web page for screen reader users, and a transcoding proxy or browser…

Arabic Accessibility(also: Arabic Language Accessibility, RTL Accessibility)

Accessibility considerations specific to Arabic language content and Arabic-speaking users. Arabic presents unique challenges for digital accessibility: the script is written right-to-left (RTL), requiring proper bidirectional text handling; letters are cursive and connect…

Aria-Live(also: ARIA Live Region, Live Region)

An ARIA attribute (aria-live) used to designate regions of a web page whose content may change dynamically, ensuring that assistive technologies announce updates to users without requiring them to navigate to the changed content. The attribute accepts values of "polite" (waits…