Glossary, References, Resources


A, AA, AAA conformance levels

In order for a Web page to conform to WCAG 2.0, all of the following conformance requirements must be satisfied:
1. Conformance Level: One of the following levels of conformance is met in full.

Note: Although conformance can only be achieved at the stated levels, authors are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.
See for a discussion on conformance.
accessibility supported
supported by users' assistive technologies as well as the accessibility features in browsers and other user agents
To qualify as an accessibility-supported use of a Web content technology (or feature of a technology), both 1 and 2 must be satisfied for a Web content technology (or feature):



alt or alternative text. See  text alternative


alternative for time-based media

document including correctly sequenced text descriptions of time-based visual and auditory information and providing a means for achieving the outcomes of any time-based interaction



ARIA is a specification for making scripts, widgets and dynamic web content accessible. It provides a means of describing roles, states, and properties for custom widgets so that they are recognizable and usable by assistive technology users. WAI-ARIA also provides a mechanism to ensure that users of assistive technologies are aware of updates in the application.
The key documents are the ARIA Specification and the ARIA Authoring Practices.

assistive technology

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents
Example: Assistive technologies that are important in the context of this document include the following:


changes of context

major changes in the content of the Web page that, if made without user awareness, can disorient users who are not able to view the entire page simultaneously
Changes in context include changes of:

Note: A change of content is not always a change of context. Changes in content, such as an expanding outline, dynamic menu, or a tab control do not necessarily change the context, unless they also change one of the above (e.g., focus).
Example: Opening a new window, moving focus to a different component, going to a new page (including anything that would look to a user as if they had moved to a new page) or significantly re-arranging the content of a page are examples of changes of context.


satisfying all the requirements of a given standard, guideline or specification . In this document conformance implies satisfying all the requirements of WCAG 2.0 AA. See: Level AA Conformance to Web Content Accessibility Guidelines 2.0
Also see A, AA, AAA WCAG conformance levels,

container element

A container element is an HTML element that contains a section of content including other HTML elements. For example, a <fieldset> groups related elements in a form. <div> is a block level generic container that you can use to group sections of block level content together.

<div role = "banner" id="header">      <!-- header content goes in here -->    </div>     
<div id="nav" role = "navigation">      <!-- navigation menu goes in here -->    </div>
<div  role = "navigation" id="sidebar1">      <!-- sidebar content goes in here -->    </div>     
<div id="main" role = "main">      <!-- main page content goes in here -->    </div>     
<div id="sidebar2" role = "navigation">      <!-- sidebar content goes in here -->    </div> 
<div id="footer">      <!-- footer content goes in here -->    </div>    

correct reading sequence

any sequence where words and paragraphs are presented in an order that does not change the meaning of the content


Dynamic HTML, or DHTML, is an umbrella term for a collection of technologies used together to create interactive and animated Websites by using a combination of a static markup language (such as HTML), a client-side scripting language (such as JavaScript), a presentation definition language (such as CSS), and the Document Object Model (DOM).


 Document Object Model/ DOM

The Document Object Model (DOM) is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents. Aspects of the DOM (such as its "elements") may be addressed and manipulated within the syntax of the programming language in use. The public interface of a DOM is specified in its application programming interface (API). (From Wikipedia, adapted)



elements / HTML element

An HTML element is an individual component of a Web page, once this has been parsed into theDOM. In the HTML syntax, most elements are written with a start tag and an end tag. Each element can have attributes, content, including other elements and text. Example: <abbr title="abbreviation">abbr.</abbr>



A programmatic message used to communicate discrete changes in the state of an object to other objects in a computational system. User input to a web page is commonly mediated through abstract events that describe the interaction and can provide notice of changes to the state of a document object.


if removed, would fundamentally change the information or functionality of the content, and information and functionality cannot be achieved in another way that would conform


The indication and setting of the actual focused element is essential both for blind and non-blind users using the keyboard. For people with visual disabilities, a method should be provided to enlarge/modify the focus indicator (typically: a dashed rectangle).
There should be a default focusable element on each page and focus should be set to this element when navigating to this page in case the entire screen changes, for partial screen changes, the focus should remain on the trigger element.


processes and outcomes achievable through user action


A compact, object-based client-side scripting language (interpreted by the Web browser) for developing client and server Internet applications. It has been originally developed by Netscape. JavaScript is no integral part of HTML, instead, its usage is mainly optimization of static Web pages for greater flexibility and more dynamic behavior (for example, client-side manipulations of the Document Object Model of the page without unnecessary server roundtrips).


A popular screen reader software program (Windows only). It uses a synthetic voice to read a computer screen out loud.

keyboard access/keyboard accessible

It allows users to access each "active" element in the portal with the keyboard. Keyboard accessibility is especially important for physically impaired and blind users who cannot use the mouse. All other users will appreciate this feature, too, especially advanced users who enter mass data, or users who work with a laptop.

keyboard interface

interface used by software to obtain keystroke input
Note 1: A keyboard interface allows users to provide keystroke input to programs even if the native technology does not contain a keyboard.
Example: A touchscreen PDA has a keyboard interface built into its operating system as well as a connector for external keyboards. Applications on the PDA can use the interface to obtain keyboard input either from an external keyboard or from other applications that provide simulated keyboard output, such as handwriting interpreters or speech-to-text applications with "keyboard emulation" functionality.
Note 2: Operation of the application (or parts of the application) through a keyboard-operated mouse emulator, such as MouseKeys, does not qualify as operation through a keyboard interface because operation of the program is through its pointing device interface, not through its keyboard interface.


text or other component with a text alternative that is presented to a user to identify a component within Web content  such as a control like a  textbox
Note 1: A label is presented to all users whereas the name may be hidden and only exposed by assistive technology. In many (but not all) cases the name and the label are the same.
Note 2: The term label is not limited to the label element in HTML.

modal window or modal dialog

In user interface design, a modal window is a child window that requires users to interact with it before they can return to operating the parent application


text by which software can identify a component within Web content to the user
Note 1: The name may be hidden and only exposed by assistive technology, whereas a label is presented to all users. In many (but not all) cases, the label and the name are the same.
Note 2: This is unrelated to the name attribute in HTML.

navigated sequentially

navigated in the order defined for advancing focus (from one element to the next) using a keyboard interface

non-text content

any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language
Note: This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text

programmatically determined (programmatically determinable)

determined by software from author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities
Example 1: Determined in a markup language from elements and attributes that are accessed directly by commonly available assistive technology.
Example 2: Determined from technology-specific data structures in a non-markup language and exposed to assistive technology via an accessibility API that is supported by commonly available assistive technology.


Attributes that are essential to the nature of a given object. As such, they are less likely to change than states; a change of a property may significantly impact the meaning or presentation of an object. Properties mainly provide limitations on objects from the most general case implied by roles without properties applied.


meaningful associations between distinct pieces of content. Relationships may be of various types to indicate which object labels another, controls another, etc.


An indicator of type. The object's role is the class of objects of which it is a member. This semantic association allows tools to present and support interaction with the object in a manner that is consistent with user expectations about other objects of that type.

same functionality

same result when used
Example: A submit "search" button on one Web page and a "find" button on another Web page may both have a field to enter a term and list topics in the Web site related to the term submitted. In this case, they would have the same functionality but would not be labeled consistently.

same relative order

same position relative to other items
Note: Items are considered to be in the same relative order even if other items are inserted or removed from the original order. For example, expanding navigation menus may insert an additional level of detail or a secondary navigation section may be inserted into the reading order.

screen reader

Screen readers are softwear programs, which are used by people who are blind to read textual information and content through synthesized speech or braille;


a dynamic property expressing characteristics of an object that may change in response to user action or automated processes. States do not affect the essential nature of the object, but represent data associated with the object or user interaction possibilities.


tab order

manages the list of element on a page that can have the focus (also known as accessibility hierarchy). These active elements are automatically added to the hierarchy by the browser when it parses the source code. By default, elements are added to the hierarchy in the order they appear in the HTML source of the page (source order).



sequence of characters that can be programmatically determined, where the sequence is expressing something in human language

text alternative

text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. Programmatically associated text is text whose location can be programmatically determined from the non-text content.
Example: An image of a chart is described in text in the paragraph after the chart. The short text alternative for the chart indicates that a description follows.
Note: Refer to Understanding Text Alternatives for more information.

text equivalents. See text alternative

used in an unusual or restricted way

words used in such a way that requires users to know exactly which definition to apply in order to understand the content correctly
Example: The term "gig" means something different if it occurs in a discussion of music concerts than it does in article about computer hard drive space, but the appropriate definition can be determined from context. By contrast, the word "text" is used in a very specific way in WCAG 2.0, so a definition is supplied in the glossary.

user agent

Any software that retrieves and renders Web content for users, such as Web browsers, media players, plug-ins, and other programs including assistive technologies that help retrieve and render Web content.
Example: Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving, rendering, and interacting with Web content.


data that is intended to be accessed by users
Note: This does not refer to such things as Internet logs and search engine monitoring data.
Example: Name and address fields for a user's account.

user interface component

a part of the content that is perceived by users as a single control for a distinct function
Note 1: Multiple user interface components may be implemented as a single programmatic element. Components here is not tied to programming techniques, but rather to what the user perceives as separate controls.
Note 2: User interface components include form elements and links as well as components generated by scripts.
Example: An applet has a "control" that can be used to move through content by line or page or random access. Since each of these would need to have a name and be settable independently, they would each be a "user interface component."

visual Impairments

impairments of the visual system. People with visual impairments range from the totally blind to people who have some difficulty reading small print.

W3C, See World Wide Web Consortium

WAI,  See Web Accessibility Initiative

Web, See World Wide Web

Web Accessibility Initiative (WAI)

The Web Accessibility Initiative (WAI) pursues, in coordination with organizations around the world, accessibility of the Web through five primary areas of work: technology, guidelines, tools, education and outreach, and research and development. (From homepage)

Web Content Accessibility Guidelines (WCAG)

The Web Content Accessibility Guidelines (WCAG) explain how to make Web content accessible to people with disabilities. The guidelines are intended for all Web content developers (page authors and site designers) and for developers of authoring tools. The primary goal of these guidelines is to promote accessibility. However, following them will also make Web content more available to all users, whatever user agent they are using (e.g., desktop browser, voice browser, mobile phone, automobile-based personal computer, etc.) or constraints they may be operating under (e.g., noisy surroundings, under- or over-illuminated rooms, in a hands-free environment, etc.). Following these guidelines will also help people find information on the Web more quickly. These guidelines do not discourage content developers from using images, video, etc., but rather explain how to make multimedia content more accessible to a wide audience. (From abstract, modified)

widget (Software Widget), Web widget

A software widget is a generic type of software application comprising portable code intended for one or more different software platforms. The term often implies that either the application, user interface, or both, are light, meaning relatively simple and easy to use, as exemplified by a desk accessory or applet, as opposed to a more complete software package such as a spreadsheet or word processor. Widgets often take the form of on-screen devices (clocks, event countdowns, auction-tickers, stock market tickers, flight arrival information, daily weather etc.).
A Web widget is a software widget for the Web. They are derived from the idea of code reuse. Other terms used to describe Web widgets include: portlet, gadget, badge, module, webjit, capsule, snippet, mini, and flake. Widgets are typically created in DHTML, JavaScript, or Adobe Flash. (From Wikipedia  adapted)

World Wide Web (WWW)

An Internet service based on the HTTP protocol and HTML pages; provides an easy-to-use user interface for the Internet.

World Wide Web Consortium (W3C)

Consortium that develops interoperable technologies (specifications, guidelines, software, and tools) to lead the Web to its full potential. W3C is a forum for information, commerce, communication, and collective understanding. (From homepage). Website:

References / Sources


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