Glossary

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AI Code Generation(also: Code Generation Model, AI Coding Assistant, LLM Code Generation)

The use of large language models and machine learning to automatically generate, suggest, or complete source code based on natural language prompts or existing code context. Tools like GitHub Copilot, ChatGPT, and Amazon CodeWhisperer are integrated into developer workflows as…

AJAX(also: Ajax, Asynchronous JavaScript and XML)

AJAX is a set of web development techniques that allow web pages to communicate with a server and update portions of the page content without requiring a full page reload. AJAX poses major accessibility challenges because dynamic content updates happen silently in the DOM,…

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

A section of a web page marked with the aria-live attribute that is dynamically updated and should be announced by assistive technologies when changes occur, even if the user's focus is elsewhere. Live regions have politeness levels: "polite" (announced at the next convenient…

Access Keys(also: Accesskeys, Keyboard Shortcuts)

Access keys are keyboard shortcuts defined in HTML using the accesskey attribute that allow users to activate or focus on specific elements — such as links or form controls — by pressing a key combination. Introduced as an accessibility feature to help keyboard-only users…

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

A programming interface provided by an operating system or UI framework that exposes information about user interface elements to assistive technologies. Accessibility APIs enable screen readers, switch access devices, and other assistive technologies to programmatically read,…

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 API(also: Accessibility Application Programming Interface, A11y API)

A set of programming interfaces provided by operating systems that allow assistive technologies and accessibility services to interact with application user interfaces. Accessibility APIs expose information about on-screen elements — their labels, roles, states, and…

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 Remediation(also: A11y Remediation, Accessibility Repair)

The process of identifying and fixing accessibility barriers in digital products such as websites, mobile applications, or documents to bring them into compliance with accessibility standards and make them usable by people with disabilities. Remediation may involve modifying…

Accessibility Repair(also: Automated Accessibility Repair, Accessibility Remediation)

Accessibility repair refers to the process of identifying and fixing accessibility barriers in digital content, ranging from manual remediation by developers to automated tools that can detect and correct certain violations programmatically. Automated repair tools aim to go…

Accessibility Tree(also: A11y Tree, Accessible Tree)

A hierarchical data structure maintained by operating systems and browsers that represents the accessible elements of a user interface in a form that assistive technologies can interpret. The accessibility tree is derived from the visual UI but organized logically rather than…

Accessibility-Oriented Prompting(also: Accessible Prompting, A11y Prompting)

A prompt engineering strategy for large language models (LLMs) in which explicit accessibility requirements are included in the prompt when requesting code generation or UI design. Rather than relying on the LLM to infer accessibility needs from generic instructions,…

Accessible Role(also: ARIA Role, Role)

An accessible role is a property that defines the type and expected behavior of a user interface element as exposed to assistive technologies through the accessibility tree. Roles communicate what an element is (e.g., button, link, heading, list, table, dialog) so that assistive…

Adaptive Rendering(also: Content Adaptation, Dynamic Rendering)

The process of automatically modifying how web content is presented based on a user's needs, preferences, or device capabilities. Adaptive rendering can involve transformations such as adjusting layout, reformatting text, replacing images with alternative representations,…

Anchor Text(also: Link Text, Hyperlink Text)

The visible, clickable text within a hypertext link that is intended to describe the link's destination or purpose. Descriptive anchor text (e.g., "download the annual report") provides clear information about what the user will find when they follow the link, while vague anchor…

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…

Aria-Live(also: ARIA Live Region, Live Region)

An ARIA attribute (aria-live) used to designate regions of a web page whose content may change dynamically, ensuring that assistive technologies announce updates to users without requiring them to navigate to the changed content. The attribute accepts values of "polite" (waits…

Authoring Tool(also: Web Authoring Tool, Content Authoring Tool)

An authoring tool is any software application used to create or modify web content, ranging from code editors and content management systems (CMS) to visual page builders and social media platforms. The W3C's Authoring Tool Accessibility Guidelines (ATAG) address two aspects of…

Auto-label(also: Automatic Labeling, Heuristic Labeling)

A feature in authoring tools or runtime environments that automatically generates accessible labels for interactive elements when a developer has not explicitly provided one. For example, Adobe Flash Player's auto-label function would heuristically find nearby text for objects…

Back-end Development(also: Server-side Development, Back-end Engineering)

The practice of building server-side logic, databases, APIs, and application architecture that power websites and applications. Back-end developers work with languages like Python, Java, Ruby, and Node.js, focusing on data processing, authentication, and business logic rather…

Browser Accessibility(also: Accessible Browsing, Web Browser Accessibility)

The degree to which web browsers themselves are usable by people with disabilities and age-related impairments, distinct from the accessibility of web content. Browser accessibility encompasses built-in features such as text zoom, high contrast modes, keyboard navigation, screen…

Browser Developer Tools(also: DevTools, Web Inspector, Developer Console)

Built-in browser utilities that allow web developers to inspect, debug, and modify web pages in real-time. Features include DOM inspection, CSS editing, JavaScript debugging, network monitoring, and performance profiling. Major browsers (Chrome, Firefox, Safari, Edge) include…

Browser Helper Object(also: BHO)

A plugin module for web browsers (originally Internet Explorer) that loads with each browser instance and has access to the Document Object Model and browser events. In accessibility contexts, BHOs have been used to implement client-side web page transformations such as text…

CAPTCHA(also: Completely Automated Public Turing test to tell Computers and Humans Apart)

A challenge-response test used on websites to determine whether a user is human, typically requiring users to identify distorted text, select images, or solve puzzles. CAPTCHAs present significant accessibility barriers, particularly for users with visual impairments who cannot…

CSS Box Model(also: Box Model)

A fundamental concept in CSS that describes how HTML elements are rendered as rectangular boxes with four distinct areas: content (the actual text or image), padding (space between content and border), border (the edge around the padding), and margin (space outside the border…

CSS Media Queries(also: Media Queries, Responsive Breakpoints)

A CSS feature that allows stylesheets to apply different rules based on characteristics of the user's device or viewport, such as screen width, resolution, color capability, or user preferences like reduced motion and high contrast. Media queries are foundational to responsive…

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…

Character Spacing(also: Letter Spacing, Tracking)

The horizontal space between individual characters in a line of text. Research has shown that increasing character spacing significantly improves reading speed and accuracy for people with dyslexia. This effect is attributed to reduced visual crowding — the phenomenon where…

Code Smell(also: Code Anti-Pattern)

A characteristic in source code that indicates a potential deeper problem, even if the code technically functions correctly. In accessibility contexts, code smells include patterns like using div or span elements instead of semantic HTML (buttons, headings, nav), inline styles…

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 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…

Contextual Learning(also: Context-Dependent Learning)

The tendency of both humans and AI systems to learn patterns and behaviours from the surrounding context rather than from abstract rules. In web development, contextual learning means that developers working on accessible codebases are more likely to produce accessible code…

Contrast Ratio(also: Color Contrast Ratio, Luminance Contrast Ratio)

A numerical measure of the difference in perceived brightness between two colors, expressed as a ratio ranging from 1:1 (no contrast) to 21:1 (maximum contrast, black on white). WCAG 2.2 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text (Level…

D3(also: D3.js, Data-Driven Documents)

A JavaScript library for producing dynamic, interactive data visualizations in web browsers using SVG, HTML, and CSS. D3 gives developers fine-grained control over visualization rendering but does not include built-in accessibility features, leaving developers responsible for…

DHTML(also: Dynamic HTML)

Dynamic HTML (DHTML) is a collective term for a combination of HTML, CSS, JavaScript, and the Document Object Model (DOM) used together to create interactive and animated web content, prevalent in the late 1990s and early 2000s. DHTML created substantial accessibility barriers…

DOM(also: Document Object Model)

A programming interface that represents an HTML or XML document as a tree structure of objects, where each node corresponds to a part of the document such as elements, attributes, and text content. The DOM is critical to accessibility because assistive technologies like screen…

DOM Manipulation(also: DOM Modification, Document Object Model Manipulation)

The programmatic modification of a webpage's Document Object Model (DOM) to change its structure, content, styling, or behavior. In accessibility contexts, DOM manipulation is used by browser extensions, accessibility overlays, and assistive tools to enhance web pages — for…

DOM Tree(also: Document Object Model, DOM)

A programming interface that represents an HTML or XML document as a hierarchical tree structure, where each node corresponds to a part of the document such as an element, attribute, or text content. Web browsers construct the DOM tree from HTML source code, and assistive…

Data Table(also: Genuine Table)

An HTML table element used to present structured, tabular information where data cells have a logical relationship to header cells. Accessible data tables require proper semantic markup including th elements for headers, scope attributes to define header direction (row or…

Decorative Image(also: Decorative Graphic, Presentational Image)

An image that serves a purely aesthetic or visual design purpose and does not convey meaningful information to the user. According to WCAG guidelines, decorative images should receive empty alt text (alt="") so that screen readers skip over them rather than announcing…

Delivery Context

Delivery context is a term defined by the W3C Device Independence Working Group to describe the set of attributes that characterize the environment in which web content is delivered and consumed. This includes device capabilities (screen size, supported markup languages, color…

Device Independence(also: Device-Independent Design, Input Agnostic Design)

A web design principle that ensures content and functionality are accessible regardless of the input device or interaction method used to access them. Device-independent design avoids assumptions about how users will interact with content — not relying solely on mouse events,…

Device-Dependent Event Handler(also: Device-Dependent Event, Mouse-Dependent Event Handler)

An event handler in web development that is triggered only by a specific input device, such as a mouse click or touch gesture, rather than being accessible through multiple input methods. Device-dependent event handlers create significant accessibility barriers because users who…

Document Object Model(also: DOM)

A programming interface for web documents that represents the page as a tree of objects, where each HTML element is a node that can be accessed and manipulated programmatically. The DOM is fundamental to web accessibility because screen readers and other assistive technologies…

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…

Dojo Toolkit(also: Dojo)

An open-source JavaScript toolkit for building Ajax web applications, notable in accessibility history for being one of the first major frameworks to incorporate WAI-ARIA support. In 2006, IBM contributed accessibility technology to Dojo, led by Becky Gibson, establishing an…

Dynamic Content(also: Dynamic Web Content, Live Content)

Dynamic content refers to web page elements that change or update after the initial page load, either automatically (such as news tickers, stock prices, or chat messages) or in response to user interaction (such as search suggestions, form validation messages, or content loaded…

Dynamic HTML(also: DHTML)

A collection of technologies — including HTML, CSS, JavaScript, and the Document Object Model (DOM) — used together to create interactive and animated web content that can change after a page has loaded without requiring a server round-trip. Dynamic HTML was a precursor to…

Focus Management(also: Focus Control, Programmatic Focus)

The practice of controlling which element on a web page or application receives keyboard focus, and ensuring that focus moves in a logical and predictable manner as users interact with the interface. Focus management is one of the most challenging aspects of web accessibility…

Form Label(also: Input Label, Form Field Label)

A text label programmatically associated with an interactive form control (such as a text input, button, checkbox, or dropdown) that identifies the purpose or function of that control to all users. In HTML, form labels are typically implemented using the <label> element linked…