Glossary

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Accessibility API(also: Accessibility Application Programming Interface, Platform Accessibility API)

A software interface provided by operating systems and browsers that exposes information about user interface elements — including their roles, states, properties, and relationships — to assistive technologies such as screen readers. Accessibility APIs (e.g., Microsoft UI…

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-supported(also: Accessibility supported technology)

A WCAG 2.0 concept describing a web technology that has sufficient support from user agents (browsers) and assistive technologies to reliably convey accessibility information to users with disabilities. For a technology to be considered accessibility-supported, it must contain…

Aural CSS(also: Aural Cascading Style Sheets, CSS Aural Properties, CSS Speech)

Aural CSS refers to CSS properties designed to control the auditory presentation of web content, originally specified as the "aural" media type in CSS2 and later revised as the "speech" media type in CSS3. These properties allow web authors to specify how content should be…

CC/PP(also: Composite Capability/Preference Profiles)

A W3C framework for describing device capabilities and user preferences using RDF (Resource Description Framework). CC/PP enables content servers to adapt the delivery of web content based on the characteristics of the requesting device and the preferences of the user, including…

Canonical MathML(also: Canonical Mathematical Markup Language)

A restricted, normalised subset of MathML in which mathematical structures are represented in a deterministic, unambiguous way. While standard Presentation MathML allows the same mathematical expression to be encoded in multiple equivalent ways, Canonical MathML enforces a…

Cascading Style Sheets(also: CSS, Stylesheets)

A stylesheet language used to describe the visual presentation of HTML documents, controlling layout, colors, fonts, spacing, and responsive design. CSS is intentionally separated from HTML content to allow flexibility in styling while prioritizing semantic structure—a design…

Default Delivery Context(also: DDC)

A baseline set of device capabilities defined by the W3C Mobile Web Best Practices specification, used as a reference point for evaluating mobile web content. The Default Delivery Context specifies minimum characteristics such as a 120-pixel screen width, XHTML Basic 1.1…

Document Object Model(also: DOM)

A programming interface that represents the structure of an HTML or XML document as a tree of objects, where each element, attribute, and piece of text becomes a node that can be programmatically accessed and manipulated. The DOM is foundational to web accessibility because…

Frame Rate(also: Frames Per Second, FPS, Frame Frequency)

Frame rate is the number of still images (frames) displayed or captured per second in a video stream, usually measured in frames per second (fps). Common values include 24 fps (cinema), 30 fps (US broadcast), and 60 fps (high-motion content); video calling and streaming systems…

Global Public Inclusive Infrastructure(also: GPII)

A framework and set of technologies designed to allow people with disabilities to automatically have their accessibility preferences and settings applied across any device, platform, or service they encounter. GPII enables portable user profiles that specify needs such as large…

HTML5 Track Element(also: <track> Element, Track Tag, HTML Track)

The HTML5 <track> element is used to specify timed text tracks for <video> and <audio> elements, providing a standardized way to associate captions, subtitles, descriptions, chapters, and metadata with media content. Each <track> element specifies a kind (captions, subtitles,…

Interoperability

The ability of different systems, devices, applications, or products to connect and communicate with each other in a coordinated way, without requiring special effort from the user. In accessibility, interoperability is critical because assistive technologies must be able to…

Longdesc(also: Long Description, longdesc Attribute)

An HTML attribute historically used to provide extended descriptions for images that require more detail than can fit in an alt attribute. The longdesc attribute contained a URL pointing to a separate page or anchor with the full description. While part of HTML 4.01 and…

MathML(also: Mathematical Markup Language)

An XML-based markup language standardized by the W3C for describing mathematical notation and capturing both its structure and content. MathML enables screen readers and other assistive technologies to interpret and convey mathematical expressions to users with visual…

MathML(also: Mathematical Markup Language)

A W3C standard XML-based markup language for describing mathematical notation and capturing both its structure and content. MathML comes in two forms: presentation MathML, which describes how a formula looks (layout and visual appearance), and content MathML, which describes…

Media Fragments(also: Media Fragments URI, Media Fragment Identifier)

Media Fragments is a W3C specification that defines a standard syntax for addressing specific portions of audio and video resources on the web using URI fragment identifiers. It allows users and applications to reference temporal segments (e.g., a specific time range within a…

Microformats(also: uFormats)

Microformats are a set of simple, open data formats built upon existing HTML standards that add machine-readable semantic meaning to web content by using standardized class names and HTML attributes. For accessibility, microformats enhance the semantic richness of web pages,…

Mobile Web Best Practices(also: MWBP, MWBP 1.0)

A W3C recommendation published in 2006 that defines good usability and accessibility practices for delivering web content to mobile devices. Derived from the Web Content Accessibility Guidelines 1.0 (WCAG 1.0), Mobile Web Best Practices focuses on guidelines that have a direct…

Mobile Web Initiative(also: MWI, W3C Mobile Web Initiative)

The W3C Mobile Web Initiative (MWI) was a program launched in 2005 to improve the experience of accessing the web from mobile devices such as cell phones and handheld systems. Operating in a manner similar to the Web Accessibility Initiative (WAI), the MWI developed best…

OWL(also: Web Ontology Language, OWL 2)

The Web Ontology Language (OWL) is a W3C standard for defining and instantiating formal ontologies on the web, enabling machines to interpret the meaning and relationships of information rather than just displaying it. OWL supports accessibility by contributing to the Semantic…

OpenMath

An XML-based standard for representing mathematical objects and their semantics in a machine-readable format. Unlike MathML, which has both presentation (visual layout) and content (semantic structure) modes, OpenMath focuses purely on semantic meaning, defining mathematical…

RDF(also: Resource Description Framework)

A W3C standard for describing resources on the web using a graph-based data model of subject-predicate-object triples. RDF provides a foundation for the Semantic Web by enabling machine-readable metadata that can describe relationships between web resources, including…

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…

SMIL(also: Synchronized Multimedia Integration Language)

A W3C XML-based markup language for describing multimedia presentations that combine audio, video, text, images, and other media with precise temporal and spatial synchronization. SMIL is significant for accessibility because it includes a MediaAccessibility module that defines…

Scalable Vector Graphics(also: SVG)

An XML-based vector image format for two-dimensional graphics that supports interactivity and animation. Unlike bitmap formats (JPEG, PNG, GIF) which store images as grids of pixels, SVG describes shapes, paths, and text mathematically, allowing images to scale without loss of…

Semantic Annotation(also: Semantic Markup, Semantic Tagging)

The process of adding machine-readable metadata to web content that describes the meaning of the content rather than its visual presentation. Unlike HTML markup which primarily specifies how content should be displayed (font size, color, layout), semantic annotations describe…

Semantic Web(also: Web of Data, Linked Data)

An extension of the World Wide Web in which information is given well-defined meaning through standardized formats and technologies (such as RDFa, OWL, and ontologies), enabling machines to interpret and process web content more intelligently. For accessibility, semantic web…

Signing Gesture Markup Language(also: SiGML)

Signing Gesture Markup Language (SiGML) is an XML-compliant notation for representing sign language gestures, developed as part of the ViSiCAST project at the University of East Anglia. SiGML is designed to bridge the gap between linguistic descriptions of signs and the…

Speech Synthesis Markup Language(also: SSML)

Speech Synthesis Markup Language (SSML) is a W3C standard XML-based markup language for controlling the rendering of synthetic speech by text-to-speech (TTS) engines. SSML provides tags for specifying pronunciation, volume, pitch, speaking rate, emphasis, pauses, and voice…

Timed Text(also: Timed Text Markup Language, TTML, DFXP)

Timed Text Markup Language (TTML) is a W3C standard for representing timed text content such as captions, subtitles, and other text synchronized with audio or video media. Originally developed as the Distribution Format Exchange Profile (DFXP), TTML provides an XML-based format…

UAProf(also: User Agent Profile)

A specification from the Open Mobile Alliance that extends the CC/PP (Composite Capability/Preference Profiles) framework to describe mobile device capabilities in a standardized RDF-based format. UAProf profiles contain information about a device's hardware platform, software…

VRML(also: Virtual Reality Modeling Language)

A file format and markup language for describing interactive 3D objects and environments on the web, first standardized in 1995. VRML allowed users to view, rotate, and navigate 3D scenes in web browsers using plugin viewers. In accessibility, VRML was used in early projects to…

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…

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…

WAP(also: Wireless Application Protocol)

A suite of protocols and specifications designed to enable mobile devices to access internet content and services. WAP defined standards for how mobile devices communicate with web servers, including markup languages (WML, XHTML-MP) optimized for small screens and limited…

Web 2.0(also: Web Two Point Oh, The Read-Write Web)

Web 2.0 refers to the shift in web development that emerged in the early 2000s, characterized by user-generated content, dynamic interfaces, rich interactivity, and social participation rather than static page delivery. For accessibility, Web 2.0 introduced significant…

Web of Things(also: WoT)

An application layer built on top of the Internet of Things (IoT) that uses open web standards — including HTTP, WebSockets, JSON-LD, and semantic web technologies — as a universal platform for interoperability between connected devices. Proposed by the W3C, the Web of Things…

WebVTT(also: Web Video Text Tracks, Web Video Text Tracks Format)

WebVTT (Web Video Text Tracks) is the W3C standard text format for providing timed text tracks — including captions, subtitles, descriptions, chapters, and metadata — synchronized with HTML5 <video> and <audio> elements. WebVTT evolved from the earlier SRT subtitle format,…

X3D(also: Extensible 3D, Extensible 3D Graphics)

An ISO-standard XML-based file format and runtime architecture for representing and communicating 3D scenes and objects on the web. X3D is the successor to VRML (Virtual Reality Modeling Language) and is maintained by the Web3D Consortium. In the accessibility context, X3D is…

XForms(also: W3C XForms)

XForms is a W3C specification for web forms that separates the purpose of a form (its data model) from its visual presentation, providing richer semantics than traditional HTML forms. Unlike HTML forms where controls are defined by their visual representation (radio buttons,…

XHTML(also: Extensible HyperText Markup Language, XHTML 1.0, XHTML 2.0)

XHTML (Extensible HyperText Markup Language) is a family of W3C specifications that reformulated HTML as an XML application, requiring stricter syntax rules such as properly nested elements, lowercase tag names, and quoted attribute values. XHTML 1.0, published in 2000, was…

XML(also: Extensible Markup Language)

A markup language designed by the W3C for encoding structured data in a format that is both human-readable and machine-readable. Unlike HTML, which has a fixed set of tags focused on presentation, XML allows authors to define custom tags that describe the meaning and structure…

XPath(also: XML Path Language)

XPath (XML Path Language) is a query language for selecting nodes and computing values from XML and HTML documents. In the context of web accessibility, XPath expressions are used by assistive technologies and accessibility tools to identify and target specific elements within a…

XSLT(also: Extensible Stylesheet Language Transformations, XSL Transformations)

A W3C standard language for transforming XML documents into other formats such as HTML, plain text, or different XML structures. XSLT uses template rules that match patterns in the source XML and produce corresponding output, enabling the separation of content from presentation.…

mobileOK(also: mobileOK Basic Tests, W3C mobileOK)

A set of machine-automatable tests published by the W3C to verify conformance with Mobile Web Best Practices 1.0. The mobileOK Basic Tests define a subset of best practices that can be unambiguously evaluated by automated tools, checking for issues such as unsupported image…

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