Glossary

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Alt text(also: Alternative text, Text alternative)

A textual description of non-text content (primarily images) provided via the HTML alt attribute, read by screen readers and displayed when images cannot be loaded. Required by WCAG Success Criterion 1.1.1 (Level A), alt text should convey the same information or function as the…

Annotation(also: Web Annotation, Content Annotation)

The practice of adding supplementary information, notes, or metadata to existing digital content, typically without modifying the original source. In accessibility, annotation is used to add alternative descriptions, labels, structural information, or other accessibility…

Audio description(also: AD, Described video, Video description)

Narration added to a media soundtrack that describes important visual information — such as actions, characters, scene changes, and on-screen text — that cannot be understood from the main audio alone. Audio description makes video and live performance content accessible to…

Augmentative and alternative communication(also: AAC, Alternative communication, Aided communication)

A range of strategies, tools, and technologies used to supplement or replace spoken or written communication for people who have difficulty producing or understanding speech. AAC encompasses unaided methods (gestures, facial expressions, sign language, body language) and aided…

Captioning(also: Captions, Closed captions, Subtitles for the deaf and hard of hearing)

The conversion of spoken dialogue, sound effects, and other auditory information into synchronised text displayed alongside audiovisual content. Captioning makes audio content accessible to people who are deaf or hard of hearing and also benefits people in noisy environments,…

Content Adaptation(also: Content Transformation, Web Adaptation)

The process of modifying web content to make it more accessible or usable in different contexts, including for users with disabilities, users of assistive technologies, or users on constrained devices like mobile phones. Content adaptation encompasses techniques such as…

Content Author(also: Content Editor, Content Creator, Web Author)

A person who creates, edits, and publishes content on a website or digital platform, typically using a content management system rather than writing code directly. Content authors are responsible for many accessibility-critical decisions including writing alternative text for…

Content Extraction(also: Web Content Extraction, Text Extraction)

The process of separating meaningful content from the surrounding structural markup, navigation elements, and boilerplate text on a web page. For assistive technology users, content extraction is valuable because it allows them to focus on the substantive information on a page…

Content Management System(also: CMS)

Software that enables users to create, edit, and publish digital content — typically web pages — without requiring direct coding knowledge. Popular examples include WordPress, Drupal, and SharePoint. In the accessibility context, CMS platforms play a critical role because they…

Controlled Language(also: CL, Controlled Natural Language)

A restricted subset of a natural language that limits vocabulary, grammar, and style to reduce ambiguity and improve clarity and consistency in writing. In accessibility, controlled language rules can be applied to verify and improve the quality of text alternatives for images,…

Curation(also: Content Curation, Accessibility Curation)

The process of selecting, organizing, and presenting digital content or resources to serve a particular audience or purpose. In accessibility contexts, curation refers to the proactive work of identifying web content that presents barriers and creating alternative, accessible…

Data visualization accessibility(also: Chart accessibility, Accessible data visualizations, Graph accessibility)

The practice of making charts, graphs, maps, dashboards, and other visual representations of data perceivable and understandable by people with disabilities, particularly screen-reader users and people with colour vision deficiencies. Most web-based visualizations are rendered…

Easy-to-Read(also: E2R, Easy Read, ETR)

A content-simplification approach that presents information in short sentences, plain vocabulary, and clear structure to support readers with cognitive disabilities, learning difficulties, low literacy, or who are reading in a non-native language. Easy-to-Read is increasingly…

Flesch Reading Ease(also: Flesch Readability Score, Flesch Score, FRE)

A readability formula developed by Rudolf Flesch in 1948 that rates text on a 100-point scale based on average sentence length and average number of syllables per word. Higher scores indicate easier-to-read text: scores of 60-70 are considered suitable for a general audience,…

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…

Image description(also: Long description, Extended image description, Image alt)

A detailed textual representation of an image's content, typically longer and more comprehensive than alt text. While alt text is a concise attribute embedded in HTML for screen readers, image descriptions may appear as visible captions, be provided via the longdesc attribute or…

Learning Object(also: LO, Reusable Learning Object, RLO)

A self-contained, reusable unit of educational content that can be independently accessed, combined with other learning objects, and delivered across different learning management systems. Learning objects can include text, multimedia, interactive exercises, assessments, or any…

Metadata

Data that provides structured information about other data or digital content. In accessibility, metadata plays a critical role in describing the accessibility features and characteristics of digital resources — for example, indicating whether a document has alternative text for…

Plain Language(also: Plain English, Clear Language, Simple Language)

Plain language is communication that is clear, concise, and well-organized so that the intended audience can easily find, understand, and use the information. In accessibility, plain language is essential for making content accessible to people with cognitive disabilities, low…

Presentation video(also: Lecture recording, Recorded lecture)

A video recording of an instructor delivering content alongside visual materials such as slides, whiteboards, or demonstrations. Presentation videos present unique accessibility challenges because they combine spoken content with visual actions like pointing, annotating, and…

Readability(also: Text Readability)

The ease with which a reader can read and understand written text. Readability encompasses both visual readability (typography, layout, color contrast, spacing) and linguistic readability (vocabulary complexity, sentence structure, text organization). In accessibility contexts,…

Readability(also: Text Readability)

The ease with which written text can be read and understood, determined by factors including vocabulary complexity, sentence length, grammatical structure, and text organisation. Readability is distinct from legibility (which concerns the visual clarity of individual characters…

Readability formula(also: readability metric, readability index, readability measure)

A mathematical formula that estimates the difficulty of reading a text, typically based on features like sentence length, word length, syllable count, or vocabulary frequency. Common formulas include Flesch Reading Ease, Flesch-Kincaid Grade Level, SMOG, and Gunning Fog Index.…

SGML(also: Standard Generalized Markup Language)

An international standard (ISO 8879:1986) metalanguage for defining markup languages that describe the structure and content of electronic documents. SGML introduced foundational concepts including descriptive markup (tagging what content is, not how it should look), document…

Sign language(also: Manual language, Visual-gestural language)

A natural language that uses manual articulation (handshapes, movement, location relative to the body), facial expressions, and body posture to convey meaning, serving as the primary or preferred language of many deaf and hard-of-hearing people. Sign languages are fully…

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 Simplification(also: Plain Language Conversion, Content Simplification)

The process of rewriting text to make it easier to read and understand, typically by using shorter sentences, simpler vocabulary, and clearer structure while preserving the essential meaning. Text simplification supports cognitive accessibility for people with intellectual…

Transcript(also: Text Transcript, Video Transcript, Audio Transcript)

A written document containing the complete text of spoken content from a video or audio recording, presented separately from the media rather than synchronized with it. Unlike captions, which appear on-screen in real time as speech occurs, transcripts provide all text at once,…

User-Generated Content(also: UGC)

Content such as text, images, videos, and reviews created and shared by end users rather than by the website or platform owner. In e-commerce, user-generated content includes customer reviews, review photos, and Q&A sections. This content poses significant accessibility…

Video Annotation(also: Video Metadata Annotation, Multimedia Annotation)

Video annotation is the process of adding supplementary information — such as text descriptions, captions, audio descriptions, or semantic labels — to specific segments or elements of a video. In accessibility contexts, video annotations provide the additional layers of…

Video accessibility(also: Accessible video, Video a11y)

The practice of making video content perceivable, operable, and understandable for people with disabilities. This encompasses captions for deaf and hard-of-hearing viewers, audio descriptions for blind users, visual enhancements for low-vision users, and controls that work with…

Web Segmentation(also: Page Segmentation, Web Page Segmentation)

The process of dividing a web page into distinct, meaningful sections or segments based on visual layout, structural markup, or content semantics. Web segmentation is important for accessibility because screen readers typically narrate content in DOM order, which may not reflect…

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