W3C Accessibility Guidelines (WCAG) 3.0

This section (with its subsections) provides requirements which must be followed to conform to the specification, meaning it is normative.

This section (with its subsections) provides requirements which must be followed to conform to the specification, meaning it is normative.

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY and MUST in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

This section (with its subsections) provides requirements which must be followed to conform to the specification, meaning it is normative.

abbreviationDeveloping

shortened form of a word, phrase, or name where the abbreviation has not become part of the language

Note 1

This includes initialisms, acronyms, and numeronyms.

1. initialisms are shortened forms of a name or phrase made from the initial letters of words or syllables contained in that name or phrase. These are not defined in all languages.
2. acronyms are abbreviated forms made from the initial letters or parts of other words (in a name or phrase) which may be pronounced as a word.
3. numeronyms are shortened forms of a word that use the first and last letters, with a number in between showing the number of letters left out.

Note 2

Some companies have adopted what used to be an initialism as their company name. In these cases, the new name of the company is the letters (for example, Ecma) and the word is no longer considered an abbreviation.

accessibility support setDeveloping

group of user agents and assistive technologies you test with

Editor's note

The AGWG is considering defining a default set of user agents and assistive technologies that they use when validating guidelines.

Accessibility support sets may vary based on language, region, or situation.

If you are not using the default accessibility set, the conformance report should indicate what set is being used.

accessibility supportedDeveloping

supported by in at least 2 major free browsers on every operating system and/or available in assistive technologies used by 80% cumulatively of the AT users on each operating system for each type of AT used

actively availableDeveloping

available for the user to read and use any actionable items included

assertionDeveloping

formal claim of fact, attributed to a person or organization, regarding procedures practiced in the development and maintenance of the content or product to improve accessibility

assistive technologyDeveloping

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

Note 1

Functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Note 2

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

Note 3

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving web content from program objects or parsing markup into identifiable bundles.

audioDeveloping

the technology of sound reproduction

Note

Audio can be created synthetically (including speech synthesis), recorded from real world sounds, or both.

audio descriptionDeveloping

narration added to the soundtrack to describe important visual details that cannot be understood from the main soundtrack alone

Note

For audiovisual media, audio description provides information about actions, characters, scene changes, on-screen text, and other visual content.

Audio description is also sometimes called “video description”, “described video”, “visual description”, or “descriptive narration”.

In standard audio description, narration is added during existing pauses in dialogue. See also extended audio description.

If all important visual information is already provided in the main audio track, no additional audio description track is necessary.

automated evaluationDeveloping

evaluation conducted using software tools, typically evaluating code-level features and applying heuristics for other tests

Note

Automated testing is contrasted with other types of testing that involve human judgement or experience. Semi-automated evaluation allows machines to guide humans to areas that need inspection. The emerging field of testing conducted via machine learning is not included in this definition.

blinkingDeveloping

switching back and forth between two visual states in a way that is meant to draw attention

Note

See also flash. It is possible for something to be large enough and blink brightly enough at the right frequency to be also classified as a flash.

blocks of textDeveloping

more than one sentence of text

camera inputDeveloping

control using a camera as a motion sensor to detect gestures of any type, for example “in the air” gestures

Note

This does not include, for example, a static QR code image on a web page.

captionsDeveloping

synchronized visual and/or text alternative for both the speech and non-speech audio portion of a work of audiovisual content

Note 1

Closed captions are equivalents that can be turned on and off with some players and can often be read using assistive technology..

Note 2

Open captions are any captions that cannot be turned off in the player. For example, if the captions are visual equivalent images of text embedded in video.

Note 3

Audio descriptions can be, but do not need to be, captioned since they are descriptions of information that is already presented visually.

Note 4

In some countries, captions are called subtitles. The term ‘subtitles’ is often also used to refer to captions that present a translated version of the audio content.

common keyboard navigation techniqueDeveloping

keyboard navigation technique that is the same across most or all applications and platforms and can therefore be relied upon by users who need to navigate by keyboard alone

Note

A sufficient listing of common keyboard navigation techniques for use by authors can be found in the WCAG common keyboard navigation techniques list

complex pointer inputDeveloping

any pointer input other than a single pointer input

componentDeveloping

grouping of elements for a distinct function

conformanceDeveloping

satisfying all the requirements of the guidelines. Conformance is an important part of following the guidelines even when not making a formal Conformance Claim

See the Conformance section for more information.

contentDeveloping

information and sensory experience to be communicated to the user by an interface, including code or markup that defines the content’s structure, presentation, and interactions

decorativeDeveloping

serving only an aesthetic purpose, providing no information, and having no functionality

Note

Text is only purely decorative if the words can be rearranged or substituted without changing their purpose.

deprecateDeveloping

declare something outdated and in the process of being phased out, usually in favor of a specified replacement

Deprecated documents are no longer recommended for use and may cease to exist in the future.

descriptive transcriptDeveloping

a text version of the speech and non-speech audio information and visual information needed to understand the content.

down eventDeveloping

platform event that occurs when the trigger stimulus of a pointer is depressed

Note

The down event may have different names on different platforms, such as “touchstart” or “mousedown”.

essential exceptionDeveloping

exception because there is no way to carry out the function without doing it this way or fundamentally changing the functionality

evaluationDeveloping

process of examining content for conformance to these guidelines

Note

Different approaches to evaluation include automated evaluation, semi-automated evaluation, human evaluation, and usability testing.

extended audio descriptionDeveloping

audio description that is added to audiovisual media by pausing the video to allow for additional time to add audio description

Note

This technique is only used when the sense of the video would be lost without the additional audio description and the pauses between dialogue or narration are too short.

figure captionsDeveloping

title, brief explanation, or comment that accompanies a work of visual media and is always visible on the page

flashDeveloping

a pair of opposing changes in relative luminance that can cause seizures in some people if it is large enough and in the right frequency range

Note 1

See general flash and red flash thresholds for information about types of flash that are not allowed.

Note 2

See also blinking.

functional needDeveloping

statement that describes a specific gap in one’s ability, or a specific mismatch between ability and the designed environment or context

general flash and red flash thresholdsDeveloping

a flash or rapidly-changing image sequence is below the threshold (i.e., content passes) if any of the following are true:

• there are no more than three general flashes and / or no more than three red flashes within any one-second period; or
• the combined area of flashes occurring concurrently occupies no more than a total of .006 steradians within any 10 degree visual field on the screen (25% of any 10 degree visual field on the screen) at typical viewing distance

where:

• A general flash is defined as a pair of opposing changes in relative luminance of 10% or more of the maximum relative luminance (1.0) where the relative luminance of the darker image is below 0.80; and where “a pair of opposing changes” is an increase followed by a decrease, or a decrease followed by an increase, and
• A red flash is defined as any pair of opposing transitions involving a saturated red

Exception: Flashing that is a fine, balanced, pattern such as white noise or an alternating checkerboard pattern with “squares” smaller than 0.1 degree (of visual field at typical viewing distance) on a side does not violate the thresholds.

Note 1

For general software or web content, using a 341 x 256 pixel rectangle anywhere on the displayed screen area when the content is viewed at 1024 x 768 pixels will provide a good estimate of a 10 degree visual field for standard screen sizes and viewing distances (e.g., 15-17 inch screen at 22-26 inches). This resolution of 75 - 85 ppi is known to be lower, and thus more conservative than the nominal CSS pixel resolution of 96 ppi in CSS specifications. Higher resolutions displays showing the same rendering of the content yield smaller and safer images so it is lower resolutions that are used to define the thresholds.

Note 2

A transition is the change in relative luminance (or relative luminance/color for red flashing) between adjacent peaks and valleys in a plot of relative luminance (or relative luminance/color for red flashing) measurement against time. A flash consists of two opposing transitions.

Note 3

The new working definition in the field for “pair of opposing transitions involving a saturated red” (from WCAG 2.2) is a pair of opposing transitions where, one transition is either to or from a state with a value R/(R + G + B) that is greater than or equal to 0.8, and the difference between states is more than 0.2 (unitless) in the CIE 1976 UCS chromaticity diagram. [ISO_9241-391]

Note 4

Tools are available that will carry out analysis from video screen capture. However, no tool is necessary to evaluate for this condition if flashing is less than or equal to 3 flashes in any one second. Content automatically passes (see #1 and #2 above).

gestureDeveloping

motion made by the body or a body part used to communicate to technology

guidelineDeveloping

high-level, plain-language outcome statements used to organize requirements

Note

Guidelines provide a high-level, plain-language outcome statements for managers, policy makers, individuals who are new to accessibility, and other individuals who need to understand the concepts but not dive into the technical details. They provide an easy-to-understand way of organizing and presenting the requirements so that non-experts can learn about and understand the concepts.

Each guideline includes a unique, descriptive name along with a high-level plain-language summary. Guidelines address functional needs on specific topics, such as contrast, forms, readability, and more.

Guidelines group related requirements and are technology-independent.

human evaluationDeveloping

evaluation conducted by a human, typically to apply human judgement to tests that cannot be fully automatically evaluated

Note

Human evaluation is contrasted with automated evaluation which is done entirely by machine, though it includes semi-automated evaluation which allows machines to guide humans to areas that need inspection. Human evaluation involves inspection of content features, in contrast with usability testing which directly tests the experience of users with content.

imagePlaceholder

Editor's note

To be defined.

informativeDeveloping

content provided for information purposes and not required for conformance. Also referred to as non-normative

interactive elementDeveloping

element that responds to user input and has a distinct programmatically determinable name

Note

In contrast to non-interactive elements. For example, headings or paragraphs.

itemsDeveloping

smallest testable unit for testing scope

Note

Items could be an interactive component such as a drop down menu, a link, or a media player.

They could also be units of content such as a phrase, a paragraph, a label or error message, an icon, or an image.

keyboard focusDeveloping

point in the content where any keyboard actions would take effect

keyboard interfaceDeveloping

API (Application Programming Interface) where software gets “keystrokes” from

Note

“Keystrokes” that are passed to the software from the “keyboard interface” may come from a wide variety of sources including but not limited to a scanning program, sip-and-puff morse code software, speech recognition software, AI of all sorts, as well as other keyboard substitutes or special keyboards.

mechanismDeveloping

process or technique for achieving a result

Note 1

The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.

Note 2

The mechanism needs to meet all requirements for the conformance level claimed.

media alternativesDeveloping

alternative formats, usually text, for audio, video, and audio-video content including captions, audio descriptions, and descriptive transcripts

methodDeveloping

detailed information, either technology-specific or technology-agnostic, on ways to meet the requirement as well as tests and scoring information

non-interactive elementDeveloping

element that does not respond to user input and does not include sub-parts

Note 1

If a paragraph included a link, the text either side of the link would be considered a static element, but not the paragraph as a whole.

Note 2

Letters within text do not constitute a “smaller part”.

non-literal languageDeveloping

words or phrases used in a way that are beyond their standard or dictionary meaning to express deeper, more complex ideas

Note

This is also called figurative language.

To understand the content, users have to interpret the implied meaning behind the words, rather than just their literal or direct meaning.

Examples include:

• allusions
• hyperbole
• idioms
• irony
• jokes
• litotes
• metaphors
• metonymies
• onomatopoeias
• oxymorons
• personification
• puns
• sarcasm
• similes

normativeDeveloping

content whose instructions are required for conformance

pageDeveloping

non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together

Note

Where a URI is available and represents a unique set of content, that would be the preferred conformance unit.

path-based gestureDeveloping

gesture that depends on the path of the pointer input and not just its endpoints

Note

Path based gesture includes both time dependent and non-time dependent path-based gestures.

platformDeveloping

software, or collection of layers of software, that lie below the subject software and provide services to the subject software and that allows the subject software to be isolated from the hardware, drivers, and other software below

Note 1

Platform software both makes it easier for subject software to run on different hardware, and provides the subject software with many services (e.g. functions, utilities, libraries) that make the subject software easier to write, keep updated, and work more uniformly with other subject software.

Note 2

A particular software component might play the role of a platform in some situations and a client in others. For example a browser is a platform for the content of the page but it also relies on the operating system below it.

Note 3

The platform is the context in which the product exists.

pointerPlaceholder

Editor's note

To be defined.

private and sensitive informationExploratory

private and sensitive information

processDeveloping

series of views or pages associated with user actions, where actions required to complete an activity are performed, often in a certain order, regardless of the technologies used or whether it spans different sites or domains

productDeveloping

testing scope that is a combination of all items, views, and task flows that make up the web site, set of web pages, web app, etc.

Note

The context for the product would be the platform.

programmatically determinableDeveloping

meaning of the content and all its important attributes can be determined by software functionality that is accessibility supported

pseudo-motion

static content on the page that gives the user the perception or feeling of motion

relative luminanceDeveloping

the relative brightness of any point in a colorspace, normalized to 0 for darkest black and 1 for lightest white

Note 1

For the sRGB colorspace, the relative luminance of a color is defined as L = 0.2126 * R + 0.7152 * G + 0.0722 * B where R, G and B are defined as:

• if RsRGB <= 0.04045 then R = RsRGB/12.92 else R = ((RsRGB+0.055)/1.055) ^ 2.4
• if GsRGB <= 0.04045 then G = GsRGB/12.92 else G = ((GsRGB+0.055)/1.055) ^ 2.4
• if BsRGB <= 0.04045 then B = BsRGB/12.92 else B = ((BsRGB+0.055)/1.055) ^ 2.4

and RsRGB, GsRGB, and BsRGB are defined as:

• RsRGB = R8bit/255
• GsRGB = G8bit/255
• BsRGB = B8bit/255

The ”^” character is the exponentiation operator. (Formula taken from [SRGB].)

Note 2

Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.

Note 3

Almost all systems used today to view web content assume sRGB encoding. Unless it is known that another color space will be used to process and display the content, authors should evaluate using sRGB colorspace.

Note 4

If dithering occurs after delivery, then the source color value is used. For colors that are dithered at the source, the average values of the colors that are dithered should be used (average R, average G, and average B).

Note 5

Tools are available that automatically do the calculations when testing contrast and flash.

Editor's note

WCAG 2.2 contains a separate page giving the relative luminance definition using MathML to display the formulas. This will need to be addressed for inclusion in WCAG 3.

requirementDeveloping

result of practices that reduce or eliminate barriers that people with disabilities experience

sectionDeveloping

self-contained portion of content that deals with one or more related topics or thoughts

Note

A section may consist of one or more paragraphs and include graphics, tables, lists and sub-sections.

semi-automated evaluationDeveloping

evaluation conducted using machines to guide humans to areas that need inspection

Note

Semi-automated evaluation involves components of automated evaluation and human evaluation.

simple pointer inputDeveloping

input event that involves only a single ‘click’ event or a ‘button down’ and ‘button up’ pair of events with no movement between

Note

Examples of things that are not simple pointer actions include double clicks, dragging motions, gestures, and any use of multipoint input or gestures, and the simultaneous use of a mouse and keyboard.

single pointerDeveloping

input modality that only targets a single point on the page/screen at a time – such as a mouse, single finger on a touch screen, or stylus

Note

Single pointer interactions include clicks, double clicks, taps, dragging motions, and single-finger swipe gestures. In contrast, multipoint interactions involve the use of two or more pointers at the same time, such as two-finger interactions on a touchscreen, or the simultaneous use of a mouse and stylus.

single pointer inputDeveloping

input modality that only targets a single point on the view at a time – such as a mouse, single finger on a touch screen, or stylus

Note 1

Single pointer interactions include clicks, double clicks, taps, dragging motions, and single-finger swipe gestures. In contrast, multipoint interactions involve the use of two or more pointers at the same time, such as two-finger interactions on a touchscreen, or the simultaneous use of a mouse and stylus.

Note 2

Single pointer input is in contrast to multipoint input such as two, three or more fingers or pointers touching the surface, or gesturing in the air, at the same time.

Note 3

Activation is usually by click or tap but can also be by programmatic simulation of a click or tap or other similar simple activation.

standard platform keyboard commandsDeveloping

keyboard commands that are the same across most or platforms and are relied upon by users who need to navigate by keyboard alone

Note

A sufficient listing of common keyboard navigation techniques for use by authors can be found in the WCAG standard keyboard navigation techniques list.

task flowDeveloping

testing scope that includes a series views that support a specified user activity

Note

A task flow may include a subset of items in a view or a group of views. Only the part of the views that support the user activity are included in a test of the task flow.

testDeveloping

mechanism to evaluate implementation of a method

textDeveloping

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

text alternativeDeveloping

text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content

up eventDeveloping

platform event that occurs when the trigger stimulus of a pointer is released

Note

The up event may have different names on different platforms, such as “touchend” or “mouseup”.

usability testingDeveloping

evaluation of the experience of users using a product or process by observation and feedback

user agentDeveloping

software that retrieves and presents external content for users

user needDeveloping

end goal a user has when starting a process through digital means

user-manipulable textDeveloping

text which the user can adjust

Note

This could include, but is not limited to, changing:

• Line, word or letter spacing
• Color
• Line length — being able to control width of block of text
• Typographic alignment — justified, flushed right/left, centered
• Wrapping
• Columns — number of columns in one-dimensional content
• Margins
• Underlining, italics, bold
• Font face, size, width
• Capitalization — all caps, small caps, alternating case
• End of line hyphenation
• Links

videoDeveloping

the technology of moving or sequenced pictures or images

Note

Video can be made up of animated or photographic images, or both.

viewDeveloping

content that is actively available in a viewport including that which can be scrolled or panned to, and any additional content that is included by expansion while leaving the rest of the content in the viewport actively available

Note

A modal dialog box would constitute a new view because the other content in the viewport is no longer actively available.

viewportDeveloping

object in which the platform presents content

Note 1

The author has no control of the viewport and almost always has no idea what is presented in a viewport (e.g. what is on screen) because it is provided by the platform. On browsers the hardware platform is isolated from the content.

Note 2

Content can be presented through one or more viewports. Viewports include windows, frames, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport. For example, nested frames. Interface components created by the user agent such as prompts, menus, and alerts are not viewports.