Glossary

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Table-to-Prose(also: Table-to-Prose Transformation, Tabular Data Narration)

The process of converting structured tabular data into natural language prose descriptions that can be easily understood when read aloud or presented through speech synthesis. Table-to-prose transformation goes beyond simple cell-by-cell linearization by constructing coherent…

Tag Order(also: Source Order, DOM Order, Reading Order)

The sequential order in which HTML elements appear in the source code of a web page, which determines the order in which screen readers and other assistive technologies present content to users. When web pages use CSS or layout tables to position content visually, the tag order…

Tagged PDF(also: Structured PDF, Accessible PDF)

A PDF document that contains semantic structure tags defining the logical reading order, headings, paragraphs, lists, tables, and figures — enabling screen readers and other assistive technologies to navigate and interpret the content meaningfully. Without tags, a PDF is…

Talking Browser(also: Talking Web Browser, Speaking Browser)

A historical term for a specialised web browser that converts on-screen content into synthesised speech, enabling blind and low-vision users to browse the web through audio rather than through a separate screen reader layered over a visual browser. Talking browsers such as IBM…

Target Size(also: Touch Target Size, Click Target Size, Hit Area)

The physical dimensions of an interactive element on screen — such as a link, button, or checkbox — that a user must point to and activate. Adequate target size is critical for users with motor impairments, tremor, or limited dexterity, as small targets require greater precision…

Task Automation(also: Web Task Automation, Browser Automation)

The use of software agents or scripts to automatically perform web-based tasks on behalf of users, such as filling forms, making purchases, or extracting information. Task automation in accessibility contexts promises to reduce the effort required for screen reader users to…

Task-Specific Navigation(also: Task-Based Browsing, Goal-Directed Navigation)

A web interaction paradigm where the interface adapts to surface content relevant to a user's specific task or goal, filtering or de-emphasizing irrelevant elements. Task-specific navigation contrasts with general-purpose browsing by using knowledge of the user's intent to…

Text Alternative(also: Alt Text, Alternative Text, Text Equivalent)

A textual replacement for non-text content, primarily images, that conveys the same purpose or information as the visual element. Text alternatives are essential for users who cannot perceive images, including people who are blind or have low vision and rely on screen readers.…

Text Alternatives(also: Text Alternative, Text Equivalent)

WCAG 2.1 Guideline 1.1 and success criterion 1.1.1 require that all non-text content (images, charts, audio, video, form controls, etc.) have a text alternative serving the equivalent purpose. Text alternatives can be presented as alt text on an image, an aria-label on a…

Text Justification(also: Text Alignment, Justified Text)

The alignment of text along the left and/or right margins of a text block. Left-aligned (ragged right) text has even spacing between words and an uneven right edge, while fully justified (left-right) text has even margins on both sides but variable word spacing. Some…

Text Reflow(also: Content Reflow, Responsive Text)

The ability of text content to rearrange and wrap within its container when the viewport is resized or text is zoomed, so that users can read without horizontal scrolling. Text reflow is essential for users with low vision who magnify content, as well as for mobile users on…

Text-Mode Browser(also: Text Browser, Terminal Browser, Console Browser)

A web browser that renders web pages as text only, without displaying images or graphical layout, typically running in a command-line terminal or console environment. The most well-known text-mode browser is Lynx, developed at the University of Kansas in the early 1990s.…

Text-Only Browser(also: Text Browser, Text-Based Browser)

A web browser that renders pages as plain text without images, styling, or complex layouts, displaying only the textual content and link structure. Examples include WebbIE, Lynx, and Links. Text-only browsers are used by some people with visual impairments as an alternative to…

Time-Based Media(also: Multimedia Content, Synchronized Media)

Content that unfolds over time, including audio, video, audio-video combinations, and interactive multimedia presentations. WCAG Guideline 1.2 requires that time-based media be made accessible through alternatives such as captions for the deaf and hard of hearing, audio…

Topic Segmentation(also: Text Segmentation, Topicalisation)

A natural language processing technique that automatically divides a document into coherent sections based on changes in topic or subject matter. Topic segmentation algorithms detect boundaries where the semantic content of adjacent sentences or paragraphs shifts significantly,…

Touch target(also: Tap target, Touch target size, Target size)

The interactive area on a touchscreen or pen-based display that responds to user input when tapped or pressed. Touch target size is a critical accessibility consideration because targets that are too small or too closely spaced cause selection errors, particularly for older…

Transcoding(also: Content transcoding, Web transcoding)

The process of converting or transforming web content from one format or structural representation to another to improve accessibility. In the context of screen reader access, transcoding can involve detecting visual layout semantics like grid structures and converting them into…

Transformation Proxy(also: Transcoding Proxy, Web Accessibility Proxy)

A transformation proxy is an intermediary server that sits between a user and the web, intercepting web pages and modifying their content before delivering them to the user's browser. In accessibility contexts, transformation proxies are used to improve the accessibility of web…

UAAG(also: User Agent Accessibility Guidelines)

A set of guidelines from the W3C Web Accessibility Initiative that explains how to make user agents — browsers, media players, and other applications that render web content — accessible to people with disabilities. UAAG addresses how user agents should support assistive…

UI Agent(also: User Interface Agent, Browser Agent, AI Agent)

An AI-powered software system that can autonomously interact with graphical user interfaces on behalf of a user, performing tasks by interpreting natural language commands and translating them into interface actions such as clicking buttons, entering text, and navigating between…

Upper Ontology(also: Foundation Ontology, Top-level Ontology)

An upper ontology is a high-level, domain-independent ontology that describes very general concepts — such as 'object', 'role', 'event', 'time', or, in a web-accessibility context, generic structural roles like 'menu', 'navigation', 'content region', or 'decoration'. It is…

Usable Accessibility

Usable accessibility is the principle that meeting technical accessibility standards (such as WCAG compliance) is necessary but not sufficient for ensuring that people with disabilities can effectively use digital products. A website may be technically accessible — screen…

User Agent(also: Browser, Web Browser)

In web accessibility, a user agent is any software that retrieves, renders, and facilitates user interaction with web content. This includes mainstream web browsers like Chrome, Firefox, and Safari, as well as assistive technologies such as screen readers that work alongside…

User-Generated Content(also: UGC, Prosumer Content)

Web content created and published by non-technical users through platforms like blogs, social media, wikis, and content management systems, rather than by professional web developers. The rise of user-generated content in Web 2.0 has created a significant accessibility…

User-Generated Content Accessibility(also: UGC Accessibility)

The practice of ensuring that user-generated content such as online reviews, forum posts, comments, and social media contributions is accessible to people with disabilities. Unlike curated website content, user-generated content poses unique accessibility challenges because it…

Verified Answer Marker(also: verified solution marker, accepted answer marker)

A visible indicator on a forum or Q&A platform signalling that a particular reply has been confirmed as correct or useful — for example, Stack Overflow's green tick, Apple Discussion Forums' top-ranked reply, or moderator-endorsed 'solution' badges. Verified markers reduce the…

Violation Score(also: Accessibility Score, A11y Score)

A numerical metric used to quantify the severity and prevalence of accessibility violations on a web page or within a dataset. Violation scores typically map qualitative impact levels (cosmetic, minor, moderate, serious, critical) to numerical values, enabling quantitative…

Violation Severity(also: Accessibility Violation Severity, Barrier Severity)

A measure of how significantly an accessibility violation impacts users with disabilities, typically rated on a scale from no violation to critical barrier. In accessibility evaluation, violation severity helps prioritize remediation efforts by distinguishing between minor…

Vision User(also: VU, Sighted User)

A person who primarily uses vision to access digital content, interacting with web pages and applications through visual scanning, mouse/trackpad pointing, and visual recognition of interface elements. Vision users can rapidly skim content, identify relevant elements through…

Vision-based Page Segmentation(also: VIPS)

A web page segmentation algorithm that uses both the source code and the visual presentation of a web page to divide it into hierarchical visual blocks. VIPS produces a tree structure where the root node represents the entire page and leaf nodes represent the smallest meaningful…

Visual Fragmentation(also: Visual Grouping, Visually Fragmented Grouping)

The design practice of organizing web page content into distinct visual groups using layout techniques such as background colors, tables, spacing, horizontal lines, and borders. Sighted users perceive these groupings at a glance and understand their roles (navigation, main…

Visual Skimming(also: Visual Scanning, Page Scanning)

The rapid visual process of scanning a page to quickly identify relevant content, key information, and areas of interest without reading every word. Sighted users can typically assess a webpage's relevance in about five seconds through visual skimming, guided by visual…

Voice Augmentation(also: Audio Augmentation, Voice-Based Augmentation)

A technique for enhancing user interfaces by adding spoken audio feedback to supplement visual information on screen. Voice augmentation provides contextual support through spoken confirmations of user input, notifications of errors or status changes, suggestions for next…

Voice Browser(also: Voice Web Browser, Audio Browser)

A voice browser is a type of web browser that presents web content through speech output and accepts voice or keyboard input rather than relying on visual display. Voice browsers convert web page content to synthesized speech using text-to-speech technology, allowing users who…

Voice Usability(also: Auditory Usability, Non-Visual Web Usability)

The degree to which a web page, application, or document is usable when accessed through a voice browser or screen reader — the audio-first counterpart to traditional visual usability. Voice usability combines structural quality (navigability — how quickly a user can reach…

VoiceXML(also: Voice Extensible Markup Language, VXML)

VoiceXML (Voice Extensible Markup Language) is a W3C standard markup language for creating voice-based user interfaces, particularly interactive voice response (IVR) systems and voice browsers. VoiceXML allows developers to define dialogs between a user and a system using…

Voicemarking(also: Voice Bookmark, Speech-Based Bookmark)

A speech-based technique for creating and retrieving semantic bookmarks in assistive web browsers. Users create voicemarks by speaking the name of a concept (e.g., "Major Headlines") and optionally a keyword, allowing them to later jump directly to that content on any website…

VoxLens

An open-source JavaScript plug-in developed at the University of Washington that improves the accessibility of online data visualizations for screen-reader users through a multimodal approach. VoxLens provides three interaction modes: a Question-and-Answer mode where users can…

W4A(also: International Cross-Disciplinary Conference on Web Accessibility, Web for All)

An annual research conference focused specifically on web accessibility, held in conjunction with the World Wide Web Conference (WWW/TheWebConf). W4A brings together researchers studying how to make the web accessible to people with disabilities, covering topics such as…

WAI-ARIA(also: ARIA, Accessible Rich Internet Applications, WAI-ARIA Specification)

A W3C technical specification that defines a set of HTML attributes (roles, states, and properties) to make dynamic web content and custom user interface widgets accessible to people using assistive technologies such as screen readers. ARIA allows developers to communicate the…

WAVE(also: WAVE Web Accessibility Evaluation Tool)

A suite of web accessibility evaluation tools developed by WebAIM (Web Accessibility In Mind) that identifies accessibility and WCAG errors in web pages. WAVE provides visual feedback by injecting icons and indicators directly into the page to show accessibility issues, making…

WCAG 2.4 Navigable(also: Guideline 2.4, Navigable Guideline)

A guideline within the Web Content Accessibility Guidelines (WCAG) under the Operable principle that requires web content to provide ways to help users navigate, find content, and determine where they are. Its success criteria address bypass blocks (skip navigation links), page…

WCAG Compliance(also: WCAG Conformance, Web Accessibility Compliance)

The degree to which a website or web application meets the requirements specified in the Web Content Accessibility Guidelines (WCAG). WCAG defines three conformance levels (A, AA, AAA) with increasingly stringent criteria. Full WCAG compliance is rare — large-scale audits find…

WCAG Conformance(also: WCAG Compliance, Web Accessibility Conformance)

The degree to which a website or web application meets the requirements defined in the Web Content Accessibility Guidelines (WCAG). WCAG defines three conformance levels: Level A (minimum, addressing the most critical barriers), Level AA (the standard target for most regulations…

WCAG Conformance Levels(also: WCAG Levels, Level A, Level AA)

WCAG defines three levels of conformance that indicate the degree to which web content meets accessibility requirements. Level A is the minimum, addressing the most critical barriers that would completely prevent some users from accessing content. Level AA is the target for most…

Web Accessibility Assessment(also: Accessibility Evaluation, Accessibility Audit, Web Accessibility Testing)

The process of evaluating websites and web applications to determine how well they meet accessibility standards and guidelines, typically WCAG. Assessment methods include automated testing with evaluation tools, manual expert review, and user testing with people with…

Web Accessibility Audit(also: Accessibility Audit, WCAG Audit)

A systematic evaluation of a website or web application against accessibility standards (typically WCAG) to identify barriers that prevent people with disabilities from accessing content. Audits may be automated (using tools like Google Lighthouse, axe, or WAVE), manual (expert…

Web Accessibility Barrier(also: WAB, Accessibility Barrier)

Any element, design pattern, or technical implementation on a web page that prevents or hinders people with disabilities from accessing, understanding, or interacting with content. Common web accessibility barriers include images without alternative text, videos without…

Web Accessibility Barrier Score(also: WAB, WAB Score)

A quantitative metric for measuring the accessibility level of a website, defined as the mean value of the failure rate of accessibility checkpoints on a page, weighted by the priority of each checkpoint. The failure rate is the number of violations of a checkpoint divided by…

Web Accessibility Evaluation(also: Accessibility Assessment, Accessibility Review)

The process of assessing whether a website or web application meets accessibility standards and can be used by people with disabilities. Evaluation methods include automated testing using tools like axe-core, WAVE, or Lighthouse; manual expert review against WCAG success…