Glossary

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Gist Summary(also: Gist, Page Gist, Web Page Summary)

A gist summary is a brief, automatically or manually generated overview of a document or web page that captures its central theme or focus, enabling a reader to quickly assess the content's relevance without reading the entire text. In accessibility contexts, gist summaries are…

Google Lighthouse(also: Lighthouse)

An open-source automated tool developed by Google for auditing web pages across multiple quality dimensions including performance, accessibility, best practices, and SEO. Lighthouse's accessibility audit checks a subset of WCAG criteria automatically, generating a score from 0…

Government Digital Accessibility(also: Public Sector Accessibility, E-Government Accessibility)

The requirement and practice of ensuring that government websites, online services, documents, and digital tools are accessible to all citizens, including those with disabilities. Many countries have enacted legislation mandating government digital accessibility, such as Section…

Graphic Accessibility(also: Image Accessibility, Visual Content Accessibility)

The practice of making graphical content — including charts, diagrams, maps, photographs, and illustrations — perceivable and understandable by people who cannot see them. Graphic accessibility encompasses a range of techniques from simple alternative text descriptions to…

Graphical Semantic Enhancement(also: Semantic Graphics, Labeled Graphics)

The practice of enriching graphical objects with meaningful text labels, descriptions, and metadata so that they can be understood non-visually. In accessible drawing and diagramming tools, graphical semantic enhancement allows users to assign descriptive labels to shapes,…

Guided Tour(also: Guided Tour Navigation, Linear Navigation Pattern)

A web navigation pattern that sequentially links content pages in a collection, allowing users to browse items one by one using next and previous controls rather than returning to an index page between each item. Guided tours reduce the cognitive and mechanical overhead of…

HSL(also: Hue Saturation Luminosity, HSL Color Model, HSB)

A colour model that represents colours using three components: Hue (the type of colour, such as red, green, or blue, expressed as a degree on a colour wheel from 0 to 360), Saturation (the purity or intensity of the colour, from grey to fully vivid), and Luminosity or Lightness…

HTML(also: HyperText Markup Language)

The standard markup language used to create and structure content on the World Wide Web. HTML uses elements (tags) to define the semantic structure of documents, including headings, paragraphs, links, lists, tables, forms, and images. Proper use of semantic HTML is fundamental…

HTML Remediation(also: Accessibility Remediation, A11y Remediation)

The process of modifying HTML code to fix accessibility violations and bring web content into conformance with accessibility guidelines like WCAG. Remediation can involve adding missing attributes (alt text, form labels, ARIA roles), correcting semantic markup (proper heading…

HTML Table(also: Data Table, Web Table)

An HTML table is a structured element in web markup used to organize data into rows and columns. Tables are created using the table, tr (table row), th (table header), and td (table data) elements. For accessibility, data tables must include proper header markup (th elements…

Heading Navigation(also: Navigate by Headings)

A screen reader navigation strategy that allows users to jump between heading elements (h1-h6) on a webpage, bypassing intermediate content to quickly find sections of interest. Heading navigation is one of the most important strategies for efficient screen reader use, but its…

Heading Structure(also: Header Hierarchy, Heading Levels, Document Outline)

The hierarchical organization of headings (H1 through H6 in HTML) used to define the logical structure and sections of a document or web page. Proper heading structure is one of the most critical accessibility features for screen reader users, who rely on headings to skim…

Heading hierarchy(also: Heading structure, Heading levels, Document outline)

The logical structure created by using HTML heading elements (h1 through h6) in a nested, hierarchical order to convey the organisation of content on a web page. A proper heading hierarchy starts with a single h1 for the page title, with h2 elements for major sections, h3 for…

Heuristic Transcoding(also: Rule-based Transcoding)

Heuristic transcoding is the automated transformation of web content to improve accessibility, device compatibility, or readability using a fixed set of predefined rules that inspect the page structure, media types, or visual characteristics — for example, rules that strip small…

Hijax(also: Progressive enhancement with Ajax)

A web development approach coined by Jeremy Keith that applies progressive enhancement principles to Ajax applications. Hijax starts with a fully functional, accessible HTML page and then layers Ajax functionality on top, so that the site degrades gracefully when JavaScript is…

Holistic Accessibility(also: Holistic Approach to Accessibility)

Holistic accessibility is an approach that considers web accessibility not as an isolated technical concern but as one factor within a broader context including usability, user experience, audience characteristics, usage environment, available technologies, and organizational…

Home Page Reader(also: IBM Home Page Reader, HPR)

A talking web browser developed by IBM Japan in the late 1990s, designed specifically for blind and low-vision users. Home Page Reader combined a web rendering engine with the ProTalker text-to-speech synthesiser and exposed navigation commands through the numeric keypad,…

Human Interaction Proof(also: HIP, Human Interactive Proof)

A challenge-response test designed to distinguish human users from automated software (bots). Human Interaction Proofs are the technical term for CAPTCHAs and similar verification systems. While effective against automated attacks, HIPs present significant accessibility…

IAccessible2(also: IA2)

An open accessibility API specification originally developed by IBM and donated to the Linux Foundation. IAccessible2 extends Microsoft Active Accessibility (MSAA) to support the richer semantic information needed by Web 2.0 applications, including WAI-ARIA roles, states, and…

IBM Home Page Reader(also: Home Page Reader, HPR)

IBM Home Page Reader (HPR) was a pioneering voice browser developed by IBM that provided audio-based web browsing for people with visual disabilities. Unlike screen readers that operate as an overlay on top of a visual browser, Home Page Reader was a self-contained browser that…

Ideographic Characters(also: Ideographs, Logograms, CJK Characters)

Ideographic characters are written symbols that represent a word, morpheme, or concept rather than an individual sound, as used in Chinese (Hanzi), Japanese (Kanji), and historically Korean (Hanja). Because a single writing system can include thousands of distinct characters —…

Image Accessibility(also: Visual Content Accessibility)

The practice of making images perceivable and understandable to people who cannot see them, primarily through alternative text descriptions. Image accessibility is a foundational requirement of WCAG (Success Criterion 1.1.1) and involves providing text alternatives that convey…

Image Map(also: Clickable Map, Imagemap)

An HTML feature that allows different regions of a single image to be designated as separate hyperlinks, each pointing to a different URL. Image maps can be client-side (coordinates and links defined in HTML MAP and AREA elements) or server-side (click coordinates sent to the…

Information Foraging(also: Information Foraging Theory)

A theoretical framework from cognitive science that models how people search for and navigate to information, drawing an analogy to animal foraging behaviour. Users assess "information scent" — cues like link text, headings, and page structure — to decide whether to continue…

Information Overload(also: Cognitive Overload, Information Overwhelm)

The state of being overwhelmed by the volume of information presented, making it difficult to identify relevant content, make decisions, or complete tasks effectively. In web accessibility contexts, information overload disproportionately affects screen reader users who must…

Information Retrieval(also: IR)

The science of searching for and extracting relevant information from large collections of documents or data. In accessibility, information retrieval techniques such as keyword extraction, text summarisation, and relevance ranking are used to help blind and visually impaired…

Information Seeking(also: Information Retrieval Behavior, Information Search)

The process of actively looking for specific information to answer a question, complete a task, or satisfy an information need. Information seeking on the web involves formulating queries, navigating search results, scanning pages for relevant content, and synthesizing…

Information wayfinding(also: Digital wayfinding, Information navigation)

The process of orienting oneself within and navigating through digital information spaces such as websites, applications, or documents, analogous to physical wayfinding through buildings or cities. For screen reader users, information wayfinding relies on structural cues like…

Interactive Description(also: Dynamic Description)

A design approach for providing accessible descriptions of interactive digital content that updates in real time as users navigate and manipulate elements. Unlike static alternative text, interactive descriptions consist of two complementary structures: state descriptions that…

Interface Consistency(also: Consistent Navigation, Consistent Identification, UI Consistency)

Interface consistency is a design principle requiring that navigational mechanisms, visual layouts, and interactive components appear and behave in the same way across different pages, screens, or applications. In accessibility, consistency is critical because users who rely on…

Internet Archive(also: Wayback Machine, Web Archive)

A non-profit digital library founded in 1996 that archives web pages, books, audio, video, and software for free public access. Its Wayback Machine service stores historical snapshots of websites, allowing researchers to view how web pages appeared at specific points in time. In…

Internet Health(also: Web Health)

A concept describing the overall state of the internet as a public resource, encompassing factors such as accessibility, privacy, security, openness, and digital inclusion. In the context of web accessibility, Internet Health refers specifically to how well the web serves people…

JIS X 8341-3(also: JIS X 8341, Japanese Industrial Standard for Web Accessibility)

JIS X 8341-3 is the Japanese Industrial Standard for web content accessibility, first published in 2004 by the Japanese Standards Association. The standard was developed with attention to harmonization with WCAG 1.0 and subsequently updated to align with WCAG 2.0. JIS X 8341-3…

Keyboard Accessibility(also: Keyboard Navigation, Keyboard Operability)

The principle and practice of ensuring that all functionality of a website, application, or digital interface can be accessed and operated using only a keyboard, without requiring a mouse, touchscreen, or other pointing device. Keyboard accessibility is foundational to web…

Keyboard Navigation(also: Keyboard Access, Keyboard Operability)

The ability to use all features and functions of a website, application, or software using only the keyboard, without requiring a mouse or other pointing device. Keyboard navigation is essential for people who are blind and use screen readers, people with motor disabilities who…

Keyword Extraction(also: Key Term Extraction, Automatic Keyword Extraction)

A natural language processing technique that automatically identifies the most important or representative words and phrases in a document. In accessibility, keyword extraction can provide blind users with a quick summary of a web page's topic without requiring them to listen to…

Landmark Navigation(also: Navigate by Landmarks, ARIA Landmark Navigation)

A screen reader navigation strategy that allows users to jump between major structural regions of a webpage defined by ARIA landmark roles (banner, navigation, main, complementary, contentinfo, search, form) or their equivalent HTML5 semantic elements. Landmark navigation…

Large-Scale Web Accessibility Evaluation(also: Large-Scale Accessibility Assessment, Web Accessibility Survey)

The systematic automated or semi-automated assessment of web accessibility across hundreds or thousands of websites to understand broad trends, compliance rates, and the overall state of accessibility on the web. These evaluations typically use automated testing tools like…

Layout Table(also: Presentational Table)

An HTML table element used to control the visual positioning of content on a web page rather than to present tabular data. Layout tables were a common web design technique before CSS became widely supported, but their use is now considered a significant accessibility barrier.…

Line Chart Accessibility(also: Accessible Line Graphs, Chart Accessibility)

The practice of making line charts and graphs perceivable and understandable by people with visual impairments through alternative representations such as tactile graphics, sonification, speech descriptions, or multimodal interfaces. Accessible line charts must convey not just…

Line Spacing(also: Leading, Line Height, Line-Height)

The vertical distance between lines of text, controlled in CSS by the line-height property. Adequate line spacing is important for readability and accessibility, particularly for people with low vision, dyslexia, or cognitive disabilities. Research shows that both younger and…

Linearization(also: Content linearization, Serial presentation)

The process by which screen readers convert two-dimensional visual page layouts into a single sequential audio stream, reading content in DOM order. Linearization strips away spatial relationships, visual groupings, and layout cues that sighted users rely on for navigation and…

Link Annotation(also: Link Augmentation, Link Labelling)

The practice of adding supplementary information to hyperlinks to help users make informed navigation decisions before clicking. In web accessibility, link annotations may include the accessibility level of the target page, the file type and size of linked documents, or…

Link Context(also: Anchor Context, Link Surrounding Context)

The text and information surrounding a hypertext link that helps users understand the link's purpose and destination. For sighted users, link context is often apparent from the visual layout — headings, images, and nearby text provide clues about what a link does. For screen…

Link Preview(also: Link Destination Preview, Link Target Preview)

Information about the content or nature of a hypertext link's destination page, provided to users before they follow the link. Link previews help users make informed navigation decisions, reducing the costly trial-and-error of following links to discover their content and then…

Link Purpose(also: Link Purpose (In Context), WCAG 2.4.4, Link Text)

A WCAG 2.4.4 Level A success criterion requiring that the purpose of each link be determinable from the link text alone, or from the link text together with its programmatically determined context (surrounding sentence, list item, table cell, containing paragraph). Links worded…

Listenability(also: Auditory Readability, Speech-Output Quality)

A web-accessibility usability metric that measures how appropriate a page's rendered text is when read aloud by a screen reader or voice browser — complementary to, and distinct from, raw WCAG conformance. Listenability penalises meaningless or placeholder ALT text (such as…

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

A section of a web page that is dynamically updated and announced by assistive technologies without requiring the user to navigate to it. Live regions are defined using the WAI-ARIA aria-live attribute, which can be set to "polite" (announced when the screen reader is idle),…

Logical Navigation(also: Structural Navigation, Semantic Navigation)

A non-visual navigation strategy in which a user moves through a web page by its semantic structure — jumping between heading levels, ARIA landmarks, skip links, form fields, or other role-tagged regions — rather than reading the content sequentially or sampling fragments by…

Long Description(also: Extended Description, longdesc)

A detailed textual description of an image or other non-text content that goes beyond the brief summary provided by alt text. Long descriptions are used for complex images such as charts, diagrams, infographics, or detailed illustrations where a short alt text cannot convey all…