Principle 1 – Perceivable

Information and user interface components must be presentable to users in ways they can perceive.

Guideline 1.1 – Text Alternatives

Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.
Advisory Techniques
  • Providing sign language videos for audio-only files (future link)

1.1.1 Non-text Content

Level A

All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below.


  • Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.)

  • Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)

  • Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.

  • Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.

  • CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.

  • Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Situation B: If a short description can not serve the same purpose and present the same information as the non-text content (e.g., a chart or diagram):
Situation D: If non-text content is time-based media (including live video-only and live audio-only); a test or exercise that would be invalid if presented in text; or primarily intended to create a specific sensory experience:
Situation F: If the non-text content should be ignored by assistive technology:
Advisory Techniques
General Techniques for Informative Non-Text Content (Advisory)
  • Identifying informative non-text content (future link)
  • Keeping short descriptions short (future link)
  • Describing images that include text (future link)
  • Providing a longer description of the non-text content where only a descriptive label is required using a technology-specific technique (for an accessibility-supported content technology) for long description listed above (future link)
  • Providing different sizes for non-text content when it cannot have an equivalent accessible alternative (future link)
  • Using server-side scripts to resize images of text (future link)
General Techniques for Live Non-Text Content (Advisory)
  • Linking to textual information that provides comparable information (e.g., for a traffic Webcam, a municipality could provide a link to the text traffic report.) (future link)
General techniques to minimize the barrier of CAPTCHAs
  • Providing more than two modalities of CAPTCHAs (future link)
  • Providing access to a human customer service representative who can bypass CAPTCHA (future link)
  • Not requiring CAPTCHAs for authorized users (future link)
HTML Techniques (Advisory)
  • H46: Using noembed with embed
  • Writing for browsers that do not support frame (future link)
  • Providing alternative content for iframe (future link)
  • Not using long descriptions for iframe (future link)
  • Providing redundant text links for client-side image maps (future link)
CSS Techniques (Advisory)
WAI-ARIA Techniques (Advisory)
  • Using the ARIA presentation role to indicate elements are purely presentational (future link)
Metadata Techniques (Advisory)
  • Using metadata to associate text transcriptions with a video (future link)
  • Using metadata to associate text transcriptions with audio-only content (future link) using one of the following techniques:
    • EXAMPLE: Providing, in metadata, URI(s) that points to an audio description and a text transcript of a video. (future link)
    • EXAMPLE: Providing, in metadata, URI(s) that point to several text transcripts (English, French, Dutch) of an audio file. (future link)

Guideline 1.2 – Time-based Media

Provide alternatives for time-based media.

1.2.1 Audio-only and Video-only (Prerecorded)

Level A

For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such:


  • Prerecorded Audio-only: An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content.

  • Prerecorded Video-only: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.

1.2.2 Captions (Prerecorded)

Level A

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.

1.2.3 Audio Description or Media Alternative (Prerecorded)

Level A

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 and is clearly labeled as such.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques

1.2.4 Captions (Live)

Level AA

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

1.2.5 Audio Description (Prerecorded)

Level AA

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

Advisory Techniques

1.2.6 Sign Language (Prerecorded)

Level AAA

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

Advisory Techniques
Metadata Techniques
  • Using metadata to associate sign language alternatives of a video to enable choice of sign language (future link) using one of the following techniques:
    • EXAMPLE: Providing, in metadata, URI(s) that point to several English sign language translations (ASL, SASL, BSL, Auslan, ISL, NZSL) of a Web page. (future link)

1.2.7 Extended Audio Description (Prerecorded)

Level AAA

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.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques

1.2.8 Media Alternative (Prerecorded)

Level AAA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Situation A: If the content is prerecorded synchronized media:
Situation B: If the content is prerecorded video-only:
Advisory Techniques

1.2.9 Audio-only (Live)

Level AAA

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

Advisory Techniques
  • Using metadata to associate text transcriptions with audio-only content (future link) using one of the following techniques:
    • Example: Providing, in metadata, URI(s) that point to several text transcripts (English, French, Dutch) of an audio file.

Guideline 1.3 – Adaptable

Create content that can be presented in different ways (for example simpler layout) without losing information or structure.

1.3.1 Info and Relationships

Level A

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Situation A: The technology provides semantic structure to make information and relationships conveyed through presentation programmatically determinable:
Situation B: The technology in use does NOT provide the semantic structure to make the information and relationships conveyed through presentation programmatically determinable:

1.3.2 Meaningful Sequence

Level A

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

Advisory Techniques
  • Using left-justified text for languages that are written left to right and right-justified text for languages that are written right-to-left (future link)
  • Providing a link to linearized rendering (future link)
  • Providing a style switcher between style sheets that affect presentation order (future link)

1.3.3 Sensory Characteristics

Level A

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques
  • Using an image with a text alternative for graphical symbols instead of a Unicode font glyph with the desired graphical appearance but different meaning (future link)

Guideline 1.4 – Distinguishable

Make it easier for users to see and hear content including separating foreground from background.
Advisory Techniques
  • Using readable fonts (future link)
  • Making sure any text in images of text is at least 14 points and has good contrast (future link)
  • Providing a highly visible highlighting mechanism for links or controls when they receive keyboard focus (future link)

1.4.1 Use of Color

Level A

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

1.4.2 Audio Control

Level A

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.

1.4.3 Contrast (Minimum)

Level AA

The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following:


  • Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;

  • Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

  • Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.

Advisory Techniques
  • G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text
  • Using a higher contrast value for text that is over a patterned background (future link)
  • Using Unicode text and style sheets instead of images of text (future link)
  • Using a higher contrast values for lines in diagrams (future link)
  • Using greater contrast level for red-black text/background combinations (future link)
  • Using colors that are composed predominantly of mid spectral components for the light and spectral extremes (blue and red wavelengths) for the dark (future link)
  • Using a light pastel background rather than a white background behind black text to create sufficient but not extreme contrast (future link)
  • Making icons using simple line drawings that meet the contrast provisions for text (future link)
  • Providing sufficient contrast ratio in graphs and charts (future link)
  • Using a 3:1 contrast ratio or higher as the default presentation (future link)
  • Providing sufficient color contrast for empty text fields (future link)

1.4.4 Resize text

Level AA

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

Advisory Techniques

1.4.5 Images of Text

Level AA

If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following:


  • Customizable: The image of text can be visually customized to the user's requirements;

  • Essential: A particular presentation of text is essential to the information being conveyed.

1.4.6 Contrast (Enhanced)

Level AAA

The visual presentation of text and images of text has a contrast ratio of at least 7:1, except for the following:


  • Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 4.5:1;

  • Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

  • Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.

Advisory Techniques
  • G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text
  • Using a higher contrast value for text that is over a patterned background (future link)
  • Using Unicode text and style sheets instead of images of text (future link)
  • Using a higher contrast values for lines in diagrams (future link)
  • Using greater contrast level for red-black text/background combinations (future link)
  • Using colors that are composed predominantly of mid spectral components for the light and spectral extremes (blue and red wavelengths) for the dark (future link)
  • Using a light pastel background rather than a white background behind black text to create sufficient but not extreme contrast (future link)
  • Making icons using simple line drawings that meet the contrast provisions for text (future link)
  • Providing sufficient contrast ratio in graphs and charts (future link)
  • Using a 3:1 contrast ratio or higher as the default presentation (future link)
  • Providing sufficient color contrast for empty text fields (future link)

1.4.7 Low or No Background Audio

Level AAA

For prerecorded audio-only content that (1) contains primarily speech in the foreground, (2) is not an audio CAPTCHA or audio logo, and (3) is not vocalization intended to be primarily musical expression such as singing or rapping, at least one of the following is true:


  • No Background: The audio does not contain background sounds.

  • Turn Off: The background sounds can be turned off.

  • 20 dB: The background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sounds that last for only one or two seconds.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques
  • Providing a way for users to adjust auditory levels of foreground and background sound independently (future link)
  • Providing an audio track for synchronized media that includes background sounds that are at least 20 decibels lower than speech (future link)

1.4.8 Visual Presentation

Level AAA

For the visual presentation of blocks of text, a mechanism is available to achieve the following:


  1. Foreground and background colors can be selected by the user.

  2. Width is no more than 80 characters or glyphs (40 if CJK).

  3. Text is not justified (aligned to both the left and the right margins).

  4. Line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing.

  5. Text can be resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Third Requirement: Techniques to ensure text is not justified (aligned to both the left and the right margins)
Fourth Requirement: Techniques to ensure line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing
Fifth Requirement: Techniques to ensure text can be resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window
Advisory Techniques
  • Using a hover effect to highlight a paragraph, list items, or table cells (CSS) (future link)
  • Presenting text in sans serif font or providing a mechanism to achieve this (CSS) (future link)
  • Using vertical (bulleted or numbered) lists rather than inline lists (future link)
  • Using upper and lower case according to the spelling conventions of the text language (future link)
  • Providing large fonts by default (future link)
  • Avoiding the use of text in raster images (future link)
  • Avoiding scaling font sizes smaller than the user-agent default (future link)
  • Providing sufficient inter-column spacing (future link)
  • Avoiding centrally aligned text (future link)
  • Avoiding chunks of italic text (future link)
  • Avoiding overuse of different styles on individual pages and in sites (future link)
  • Making links visually distinct (future link)
  • Providing expandable bullets (future link)
  • Show/hide bullet points (future link)
  • Putting an em-space or two spaces after sentences (future link)

1.4.9 Images of Text (No Exception)

Level AAA

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

Principle 2 – Operable

User interface components and navigation must be operable.

Guideline 2.1 – Keyboard Accessible

Make all functionality available from a keyboard.

2.1.1 Keyboard

Level A

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 and not just the endpoints.

Advisory Techniques
  • Using XHTML role, state, and value attributes if repurposing static elements as interactive user interface components (future link) AND SCR29: Adding keyboard-accessible actions to static HTML elements (Scripting)
  • Providing keyboard shortcuts to important links and form controls (future link)
  • Using unique letter combinations to begin each item of a list (future link)
  • Choosing the most abstract event handler (Scripting) (future link)
  • Using the onactivate event (Scripting) (future link)
  • Avoiding use of common user-agent keyboard commands for other purposes (future link)

2.1.2 No Keyboard Trap

Level A

If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away.

2.1.3 Keyboard (No Exception)

Level AAA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

  • No additional techniques exist for this Success Criterion. Follow techniques for Success Criterion 2.1.1. If that is not possible because there is a requirement for path-dependent input, then it is not possible to meet this Level AAA Success Criterion.

Guideline 2.2 – Enough Time

Provide users enough time to read and use content.

2.2.1 Timing Adjustable

Level A

For each time limit that is set by the content, at least one of the following is true:


  • Turn off: The user is allowed to turn off the time limit before encountering it; or

  • Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or

  • Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or

  • Real-time Exception: The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or

  • Essential Exception: The time limit is essential and extending it would invalidate the activity; or

  • 20 Hour Exception: The time limit is longer than 20 hours.

Advisory Techniques
  • Using a script to poll the server and notify a user if a time limit is present (Scripting) (future link)
  • Using sounds to focus user's attention (future link)

2.2.2 Pause, Stop, Hide

Level A

For moving, blinking, scrolling, or auto-updating information, all of the following are true:


  • Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and

  • Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.

Advisory Techniques
  • Providing a mechanism to stop all content that blinks within a Web page (future link)
  • Providing the user with a means to stop moving content even if it stops automatically within 5 seconds (future link)

2.2.4 Interruptions

Level AAA

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

2.2.5 Re-authenticating

Level AAA

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

Guideline 2.3 – Seizures

Do not design content in a way that is known to cause seizures.
Advisory Techniques
  • Ensuring that content does not violate spatial pattern thresholds (future link)

2.3.1 Three Flashes or Below Threshold

Level A

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.

Advisory Techniques
  • Reducing contrast for any flashing content (future link)
  • Avoiding fully saturated reds for any flashing content (future link)
  • Reducing the number of flashes even if they do not violate thresholds (future link)
  • Providing a mechanism to suppress any flashing content before it begins (future link)
  • Slowing down live material to avoid rapid flashes (as in flashbulbs) (future link)
  • Freezing the image momentarily if 3 flashes within one second are detected (future link)
  • Dropping the contrast ratio if 3 flashes within one second are detected (future link)
  • Allowing users to set a custom flash rate limit (future link)

2.3.2 Three Flashes

Level AAA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques
  • Reducing contrast for any flashing content (future link)
  • Avoiding fully saturated reds for any flashing content (future link)
  • Reducing the number of flashes even if they don't violate thresholds (future link)
  • Slowing down live material to avoid rapid flashes (as in flashbulbs) (future link)
  • Freezing the image momentarily if 3 flashes within one second are detected (future link)
  • Dropping the contrast ratio if 3 flashes within one second are detected (future link)
Provide ways to help users navigate, find content, and determine where they are.
Advisory Techniques
  • Limiting the number of links per page (future link)
  • Providing mechanisms to navigate to different sections of the content of a Web page (future link)
  • Making links visually distinct (future link)
  • Highlighting search terms (future link)

Principle 3 – Understandable

Information and the operation of user interface must be understandable.

Guideline 3.1 – Readable

Make text content readable and understandable.
Advisory Techniques
  • Setting expectations about content in the page from uncontrolled sources (future link)
  • Providing sign language interpretation for all content (future link)
  • Using the clearest and simplest language appropriate for the content (future link)
  • Avoiding centrally aligned text (future link)
  • Avoiding text that is fully justified (to both left and right margins) in a way that causes poor spacing between words or characters (future link)
  • Using left-justified text for languages that are written left to right and right-justified text for languages that are written right-to-left (future link)
  • Limiting text column width (future link)
  • Avoiding chunks of italic text (future link)
  • Avoiding overuse of different styles on individual pages and in sites (future link)
  • Making links visually distinct (future link)
  • Using images, illustrations, video, audio, or symbols to clarify meaning (future link)
  • Providing practical examples to clarify content (future link)
  • Using a light pastel background rather than a white background behind black text (future link)
  • Avoiding the use of unique interface controls unnecessarily (future link)
  • Using upper and lower case according to the spelling rules of the text language (future link)
  • Avoiding unusual foreign words (future link)
  • Providing sign language versions of information, ideas, and processes that must be understood in order to use the content (future link)
  • Making any reference to a location in a Web page into a link to that location (future link)
  • Making references to a heading or title include the full text of the title (future link)
  • Providing easy-to-read versions of basic information about a set of Web pages, including information about how to contact the Webmaster (future link)
  • Providing a sign language version of basic information about a set of Web pages, including information about how to contact the Webmaster (future link)

3.1.1 Language of Page

Level A

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

3.1.2 Language of Parts

Level AA

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.

Advisory Techniques

3.1.3 Unusual Words

Level AAA

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

Advisory Techniques
  • Using markup and visual formatting to help users recognize words that have special meaning (future link)
  • Providing a voice-enabled dictionary search so that users who have difficulty typing or spelling can speak the word whose definition they need (future link)
  • Providing a sign language dictionary to help users who are deaf find the necessary definitions (future link)
  • Providing a mechanism for finding definitions for all words in text content (future link)
  • Providing a mechanism to determine the meaning of each word or phrase in text content (future link)
  • Avoiding unusual foreign words (future link)
  • Using a series of dictionaries in cascading fashion to provide meanings (future link)

3.1.4 Abbreviations

Level AAA

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

Advisory Techniques
  • Using unique abbreviations in a Web page (future link)
  • Using visual formatting to help users recognize abbreviations (future link)
  • Providing access to a talking dictionary to support users who might have difficulty decoding written definitions (future link)
  • Providing a voice-enabled dictionary search so that users who have difficulty typing or spelling can speak the word whose definition they need (future link)

3.1.5 Reading Level

Level AAA

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.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

  • Note: Different sites may address this Success Criterion in different ways. An audio version of the content may be helpful to some users. For some people who are deaf, a sign language version of the page may be easier to understand than a written language version since sign language may be their first language. Some sites may decide to do both or other combinations. No technique will help all users who have difficulty. So different techniques are provided as sufficient techniques here for authors trying to make their sites more accessible. Any numbered technique or combination above can be used by a particular site and it is considered sufficient by the Working Group.
Advisory Techniques
  • Providing text for navigational and landing pages that requires reading ability that is less advanced than the lower secondary education level (future link)
  • Providing text for interior pages that requires reading ability at the lower secondary education level (future link)
  • Including content summaries in metadata (future link)
  • Using the clearest and simplest language appropriate for the content (future link)
  • Using RDF to associate supplements with primary content (future link)
  • Providing a clear representational image on the site's home page (future link)
  • Clearly marking, by use of text or icon, content which has been optimized for easy reading (future link)
  • Using sentences that contain no redundant words, that is, words that do not change the meaning of the sentence (future link)
  • Using sentences that contain no more than two conjunctions (future link)
  • Using sentences that are no longer than the typical accepted length for secondary education (Note: In English that is 25 words) (future link)
  • Using sentences that do not contain complex words or phrases that could be replaced with more commonly used words without changing the meaning of the sentence (future link)
  • Providing summaries for different sections of text (future link)
  • Using metadata to associate alternatives at different reading levels. (future link)
  • Using the Dublin Core accessibility element to associate text content with text, graphical, or spoken supplements (future link)
  • Using the ISO AfA accessibility element to associate text content with text, graphical, or spoken supplements (future link)
  • Using the IMS accessibility element to associate text content with text, graphical, or spoken supplements (future link)
  • Making metadata viewable by humans (future link) using one of the following techniques:
    • EXAMPLE: Providing, in metadata, URI(s) that point to a pre-primary-reading-level and a primary-reading-level text transcript of a new scientific discovery advanced-reading-level article. (future link)
  • Providing progressive complexity for site and page content (future link)

3.1.6 Pronunciation

Level AAA

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

Advisory Techniques
  • Providing pronunciations in a sound file, so that users can listen to the pronunciations of the word (future link)
  • Providing a mechanism for finding pronunciations for all foreign words in text content (future link)
  • Providing a mechanism to determine the pronunciations of each word or phrase in text content (future link)

Guideline 3.2 – Predictable

Make Web pages appear and operate in predictable ways.
Advisory Techniques
  • Positioning labels to maximize predictability of relationships (future link)

3.2.1 On Focus

Level A

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

  • Note: A change of content is not always a change of context. This success criterion is automatically met if changes in content are not also changes of context.
Advisory Techniques

3.2.2 On Input

Level A

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.

3.2.3 Consistent Navigation

Level AA

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.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques

3.2.4 Consistent Identification

Level AA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

  • Note 1: Text alternatives that are “consistent” are not always “identical.” For instance, you may have an graphical arrow at the bottom of a Web page that links to the next Web page. The text alternative may say “Go to page 4.” Naturally, it would not be appropriate to repeat this exact text alternative on the next Web page. It would be more appropriate to say “Go to page 5”. Although these text alternatives would not be identical, they would be consistent, and therefore would satisfy this Success Criterion.
  • Note 2: A single non-text-content-item may be used to serve different functions. In such cases, different text alternatives are necessary and should be used. Examples can be commonly found with the use of icons such as check marks, cross marks, and traffic signs. Their functions can be different depending on the context of the Web page. A check mark icon may function as “approved”, “completed”, or “included”, to name a few, depending on the situation. Using “check mark” as text alternative across all Web pages does not help users understand the function of the icon. Different text alternatives can be used when the same non-text content serves multiple functions.
Advisory Techniques
  • Ensuring that the text alternative conveys the function of the component and what will happen when the user activates it (future link)
  • Using the same non-text content for a given function whenever possible (future link)

3.2.5 Change on Request

Level AAA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques

Guideline 3.3 – Input Assistance

Help users avoid and correct mistakes.
Advisory Techniques
  • Hiding optional form fields (future link)

3.3.1 Error Identification

Level A

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.

Advisory Techniques

3.3.2 Labels or Instructions

Level A

Labels or instructions are provided when content requires user input.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

  • Note: The techniques at the end of the above list should be considered “last resort” and only used when the other techniques cannot be applied to the page. The earlier techniques are preferred because they increase accessibility to a wider user group.

3.3.3 Error Suggestion

Level AA

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

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Advisory Techniques
  • G139: Creating a mechanism that allows users to jump to errors
  • Making error messages easy to understand and distinguishable from other text in the Web page (future link)
  • Validating form submissions on the server (future link)
  • When mandatory information has not been provided, including descriptions or examples of correct information in addition to identifying the field as mandatory (future link)
  • Repeating and emphasizing suggestions for correcting each input error in the context of its form field (future link)
  • Providing a way for the user to skip from each item in a list of suggestions to its corresponding form field (future link)
  • Providing additional contextual help for the form field requiring change (future link)
  • Accepting input data in a variety of formats (future link)
  • G199: Providing success feedback when data is submitted successfully
    Techniques for providing suggestions to the user (Advisory)
    • Providing a text description that contains information about the number of input errors, suggestions for corrections to each item, and instructions on how to proceed (future link)
    • Providing a text description that contains suggestions for correction as the first item (or one of the first items) of content, or emphasizing this information in the content (future link)
    • Displaying errors and suggestions in the context of the original form (for example, re-displaying a form where input errors and suggestions for correction are highlighted and displayed in the context of the original form) (future link)
    HTML Techniques (Advisory)
    • Providing "correct examples" for data and data formats as initial text in mandatory form fields (future link)
    • Providing links to suggested correction text "close to" form fields, or providing the suggested correction text itself directly on the Web page "next to" form fields (future link)
    Client-Side Scripting Techniques (Advisory)

3.3.4 Error Prevention (Legal, Financial, Data)

Level AA

For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true:


  1. Reversible: Submissions are reversible.

  2. Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.

  3. Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

Advisory Techniques

3.3.5 Help

Level AAA

Context-sensitive help is available.

3.3.6 Error Prevention (All)

Level AAA

For Web pages that require the user to submit information, at least one of the following is true:


  1. Reversible: Submissions are reversible.

  2. Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.

  3. Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Principle 4 – Robust

Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

Guideline 4.1 – Compatible

Maximize compatibility with current and future user agents, including assistive technologies.
Advisory Techniques
  • Avoiding deprecated features of W3C technologies (future link)
  • Not displaying content that relies on technologies that are not accessibility-supported when the technology is turned off or not supported. (future link)

4.1.1 Parsing

Level A

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 the specifications allow these features.

4.1.2 Name, Role, Value

Level A

For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

Sufficient Techniques

Note: Other techniques may also be sufficient if they meet the success criterion. See Understanding Techniques.

Situation B: If using script or code to re-purpose a standard user interface component in a markup language:
Advisory Techniques
  • Providing labels for all form controls that do not have implicit labels (future link)

Contribute

We welcome feedback and suggestions: