WCAG 2.1 Erfolgskriterien-Referenz

All non-text content presented to users has a text alternative that serves an equivalent purpose, with specific exceptions for controls, tests, CAPTCHA, and decorative content.

For prerecorded audio-only and video-only content, an alternative is provided: a text transcript for audio-only, and either a text alternative or audio track for video-only.

Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such.

An alternative for time-based media or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text.

Captions are provided for all live audio content in synchronized media.

Audio description is provided for all prerecorded video content in synchronized media.

Sign language interpretation is provided for all prerecorded audio content in synchronized media.

Where pauses in foreground audio are insufficient to allow audio descriptions to convey the sense of the video, extended audio description is provided for all prerecorded video content in synchronized media.

An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media.

An alternative for time-based media that presents equivalent information for live audio-only content is provided.

Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined.

Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.

Content does not restrict its view and operation to a single display orientation (portrait or landscape) unless a specific orientation is essential.

The purpose of each input field collecting information about the user can be programmatically determined when the field serves a purpose listed in the Input Purposes for User Interface Components section.

In content implemented using markup languages, the purpose of user interface components, icons, and regions can be programmatically determined.

Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

If any audio on a web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.

Text and images of text have a contrast ratio of at least 4.5:1, with exceptions for large text (3:1), incidental text, and logotypes.

Text can be resized without assistive technology up to 200 percent without loss of content or functionality, except for captions and images of text.

Text is used to convey information rather than images of text, except when the image is essential or can be visually customized.

Text and images of text have a contrast ratio of at least 7:1, with exceptions for large text (4.5:1), incidental text, and logotypes.

For prerecorded audio-only content that contains primarily speech in the foreground and is not an audio CAPTCHA or audio logo, background sounds can be turned off, or are at least 20 dB lower than the foreground speech content.

For the visual presentation of blocks of text, a mechanism is available to achieve specific visual requirements including foreground/background color selection, line width under 80 characters, full justification avoidance, line spacing, and text resizing without assistive technology.

Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed.

Content can be presented without loss of information or functionality, and without requiring scrolling in two dimensions, for vertical scrolling content at a width equivalent to 320 CSS pixels and for horizontal scrolling content at a height equivalent to 256 CSS pixels. Exceptions apply for content requiring two-dimensional layout.

Visual presentation of user interface components and graphical objects have a contrast ratio of at least 3:1 against adjacent colors, with exceptions for inactive components and where appearance is determined by the user agent.

No loss of content or functionality occurs when users set line height to at least 1.5 times the font size, letter spacing to at least 0.12 times the font size, word spacing to at least 0.16 times the font size, and space after paragraphs to at least 2 times the font size.

Where receiving and then removing pointer hover or keyboard focus triggers additional content to become visible and then hidden, the additional content is dismissible, hoverable, and persistent.

All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement.

If keyboard focus can be moved to a component using a keyboard interface, then focus can be moved away from that component using only a keyboard interface; if this requires more than unmodified arrow or Tab keys, users are advised of the method for moving focus away.

All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes.

If a keyboard shortcut is implemented using only letter, punctuation, number, or symbol characters, then a mechanism is available to turn off, remap, or activate only on focus.

For each time limit set by the content, users can turn off, adjust, or extend the limit unless the time limit is essential or exceeds 20 hours.

For moving, blinking, scrolling, or auto-updating information that starts automatically and lasts more than 5 seconds and is presented in parallel with other content, a mechanism is available for users to pause, stop, or hide it.

Timing is not an essential part of the event or activity presented by the content, except for non-interactive synchronized media and real-time events.

Interruptions can be postponed or suppressed by the user, except for interruptions involving an emergency.

When an authenticated session expires, users can continue the activity without loss of data after re-authenticating.

Users are warned of the duration of any user inactivity that could cause data loss, unless the data is preserved for more than 20 hours of user inactivity.

Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.

Web pages do not contain anything that flashes more than three times in any one second period.

Motion animation triggered by interaction can be disabled, unless the animation is essential to the functionality or the information being conveyed.

A mechanism is available to bypass blocks of content that are repeated on multiple web pages.

Web pages have titles that describe topic or purpose.

If a web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operation.

The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general.

More than one way is available to locate a web page within a set of web pages, except where the web page is the result of, or a step in, a process.

Headings and labels describe topic or purpose.

Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.

Information about the user's location within a set of web pages is available.

A mechanism is available to allow the purpose of each link to be identified from link text alone, except where the purpose of the link would be ambiguous to users in general.

Section headings are used to organize the content.

All functionality that uses multipoint or path-based gestures for operation can be operated with a single pointer without a path-based gesture, unless a multipoint or path-based gesture is essential.

For functionality that can be operated using a single pointer, at least one of the following is true: no down-event, abort or undo, up reversal, or essential.

For user interface components with labels that include text or images of text, the name contains the text that is presented visually.

Functionality that can be operated by device motion or user motion can also be operated by user interface components, and responding to the motion can be disabled to prevent accidental actuation.

The size of the target for pointer inputs is at least 44 by 44 CSS pixels, with exceptions for inline links, user-agent controls, and essential targets.

Web content does not restrict use of input modalities available on a platform except where the restriction is essential, required to ensure the security of the content, or required to respect user settings.

The default human language of each web page can be programmatically determined.

The human language of each passage or phrase in the content can be programmatically determined, except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text.

A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon.

A mechanism for identifying the expanded form or meaning of abbreviations is available.

When text requires reading ability more advanced than the lower secondary education level after removal of proper names and titles, supplemental content or a version that does not require reading ability more advanced than the lower secondary education level is available.

A mechanism is available for identifying specific pronunciation of words where meaning of the words, in context, is ambiguous without knowing the pronunciation.

When any user interface component receives focus, it does not initiate a change of context.

Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component.

Navigational mechanisms that are repeated on multiple web pages within a set of web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user.

Components that have the same functionality within a set of web pages are identified consistently.

Changes of context are initiated only by user request, or a mechanism is available to turn off such changes.

If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

Labels or instructions are provided when content requires user input.

If an input error is automatically detected and suggestions for correction are known, then the suggestion is provided to the user, unless it would jeopardize the security or purpose of the content.

For web pages that cause legal commitments or financial transactions, modify or delete user-controllable data, or submit user test responses, submissions are reversible, verified, or confirmed.

Context-sensitive help is available.

For web pages that require the user to submit information, at least one of reversible, checked, or confirmed is true.

In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique — except where specifications allow these features.

For all user interface components, the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically determined; and notification of changes is available to user agents, including assistive technologies.

In content implemented using markup languages, status messages can be programmatically determined through role or properties such that they can be presented to the user by assistive technologies without receiving focus.