Glossary
Searchable terminology from accessibility, web standards, and related fields.
19 results found in web.
- ARIA (Accessible Rich Internet Applications, WAI-ARIA)
- A W3C specification that provides a framework of roles, states, and properties to make dynamic web content and custom user interface controls accessible to assistive technologies. ARIA supplements HTM…
- Adaptive content (Content adaptation, Adaptive hypermedia)
- Content that automatically adjusts its presentation, structure, or level of detail based on the needs, preferences, or capabilities of the user or their device. In accessibility, adaptive content goes…
- Alt text (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 …
- Audio description (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…
- Captioning (Captions, Closed captions, Subtitles for the deaf and hard of hearing, SDH)
- 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…
- Colour blindness (Color blindness, Colour vision deficiency, CVD)
- A condition affecting the perception of colour, caused by absent or altered photoreceptors in the retina. The main types are classified by which colour receptors are affected: protanopia (absent red r…
- Colour contrast ratio (Contrast ratio, Luminance contrast ratio, Color contrast)
- A numerical measure of the perceived brightness difference between a foreground colour (typically text) and its background, expressed as a ratio ranging from 1:1 (no contrast, identical colours) to 21…
- Data visualization accessibility (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 peopl…
- Dexter Model (Dexter Hypertext Reference Model)
- A reference model for hypertext systems published in 1988 that defines the fundamental concepts of components, links, anchors, and presentation specifications. The Dexter Model was created as a supers…
- Hypermedia
- An extension of hypertext that incorporates multimedia content — audio, video, images, and animation — alongside text, all linked in a non-linear structure. What distinguishes hypermedia from hypertex…
- Hypertext
- A way of organising and presenting textual content in a non-linear manner by breaking it into fragments and describing the relationships between them. A book has chapters in a fixed order, but hyperte…
- Image description (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 descrip…
- Photosensitive epilepsy (PSE, Photosensitivity, Visually-provoked epilepsy)
- A form of epilepsy in which seizures are triggered by visual stimuli such as flashing lights, strobing effects, rapid colour transitions, or high-contrast repeating patterns. It affects approximately …
- SVG (Scalable Vector Graphics)
- An XML-based markup language for describing two-dimensional vector graphics, widely used on the web for icons, illustrations, data visualizations, and interactive graphics. Unlike raster images (JPEG,…
- Semantic HTML
- The practice of using HTML elements according to their intended meaning rather than their visual appearance. Semantic elements like <nav>, <main>, <article>, <aside>, and <header> communicate the stru…
- Variable Font (OpenType Variable Font, Parametric Font)
- A font file that contains multiple design variations along one or more continuous axes — weight, width, slant, optical size, or custom axes — allowing any intermediate value to be rendered at run time…
- Virtual environment (Virtual world, VR environment, 3D virtual space)
- A computer-generated simulation of a three-dimensional space that users can navigate and interact with, typically rendered visually through screens or head-mounted displays. Virtual environments range…
- W3C (World Wide Web Consortium)
- The main international standards organisation for the World Wide Web, founded by Tim Berners-Lee in 1994. The W3C develops and maintains specifications including HTML, CSS, SVG, and ARIA. Its Web Acce…
- WCAG (Web Content Accessibility Guidelines, WCAG 1.0, WCAG 2.0, WCAG 2.1, WCAG 2.2)
- A set of guidelines published by the W3C Web Accessibility Initiative (WAI) that define how to make web content more accessible to people with disabilities. WCAG is organized around four principles: P…