W3C logo

Web Content Accessibility Guidelines 2.0

W3C Working Draft 31 July 2001

This version:
Latest version:
Previous version:
Wendy Chisholm, W3C
Jason White, University of Melbourne
Gregg Vanderheiden, Trace R&D Center

Copyright 2001 W3C (MIT, INRIA, Keio ), All Rights Reserved. W3C liability, trademark, document useand software licensing rules apply. Your interactions with this site are in accordance with our public and Member privacy statements.


W3C published the Web Content Accessibility Guidelines 1.0 (WCAG 1.0) as a Recommendation in May 1999. This Working Draft for version 2.0 builds on WCAG 1.0. It has the same aim: explain how to make Web content accessible to people with disabilities. Incorporating feedback on WCAG 1.0, this Working Draft of version 2.0 focuses on checkpoints. It attempts to apply checkpoints to a wider range of technologies and to use wording that may be understood by a more varied audience.

Status of this document

This document is prepared by the Web Content Accessibility Guidelines Working Group (WCAG WG) to show how more generalized (less HTML-specific) WCAG checkpoints might read. This draft is not based on consensus of the WCAG Working Group nor has it gone through W3C process. This Working Draft in no way supersedes WCAG 1.0.

Significant changes from the last draft are marked "[Proposed]."

Please refer to "Issue Tracking for WCAG 2.0" for a list of open issues related to this Working Draft. The "History of Changes to WCAG 2.0 Working Drafts" is also available.

This is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of current W3C Recommendations and other technical documents is available.

Please send comments on this document to w3c-wai-gl@w3.org. The archives for this list are publicly available.

Table of Contents



This document outlines design principles for usable, attractive, andaccessible Web sites. When these principles are ignored, individuals with disabilities may not be able to access the content at all, or they may be able to do so only with great difficulty. When these principles are employed, they also make Web content accessible to a variety of Web-enabled devices, such as phones, handheld devices, kiosks, network appliances, etc. By making content accessible to a variety of devices, the content is now accessible to people in a variety of situations.

Have you ever read the captions on a TV in a store because the background noise made it difficult to hear?

Not all devices are the same. Not all systems are the same. Not all people are the same. In following the guidelines, attempt to reach the maximum number of people in the maximum number of scenarios. This can be achieved through a single accessible rendering or multiple accessible renderings optimized for different situations.

The design principles in this document represent broad concepts that apply to all Web-based content. They are not specific to HTML, XML, or any other technology. This approach was taken so that the design principles could be applied to a variety of situations and technologies, including those that do not yet exist.

How to read this document

It takes a variety of people to make a Web site, therefore it will take a variety of people to make it accessible. All of the information and guidance we offer to make Web sites accessible is gathered in a suite of documents. At the top layer is the most general of the concepts the bottom layer is the most specific of the concepts.

Top layer - Overview of Design Principles, Guidelines, Checkpoints

The top layer, where you are now, is divided into an Overview of Design Principles and 4 Guidelines:

Each Guideline has several Checkpoints associated with it. There are a total of 2X checkpoints.

Each checkpoint is divided into normative and non-normative (informative) information. The normative text is what you must conform to. The informative text only helps to make the normative text easier to understand. A checkpoint consists of:

Bottom layer - Technology specific information

In separate Techniques Documents are code examples, screen shots, and other information specific to a technology.

These will become active links as the corresponding working drafts are published.


We expect that policy makers will use the Guideline and Checkpoint level, while developers will dive into Techniques and managers might only need to read the Overview of Design Principles.


@@accessibility vs usability? Refer to the Limitations section in Paul's intro.

Priorities and Techniques

This WCAG 2.0 Working Draft does not assign priorities to checkpoints, nor does it include links to technology-specific examples and techniques. Later versions of this document will assign priorities and will link to techniques. This Working Draft presents an initial reorganization and begins to incorporate other feedback received since the publication of WCAG 1.0 in May 1999.

In some cases, WCAG 1.0 checkpoints of various priorities are combined into a single checkpoint in the WCAG 2.0 Working Draft. In these instances, a priority cannot be assigned to the new checkpoint until the WCAG Working Group has extensively discussed the priority for that checkpoint. Priorities will be included in a future Working Draft.

The WCAG Working Group is proceeding carefully to minimize substantial differences between the WCAG 1.0 Recommendation and the WCAG 2.0 Working Draft. Refer to the Checkpoint Mapping Between WCAG 1.0 and WCAG 2.0 Working Draft for more detail on current correspondences.

WCAG 1.0 is accompanied by supporting techniques documents (non-normative) which include examples of how to implement WCAG 1.0 in HTML and CSS. The WCAG Working Group will continue to develop the HTML and CSS technique documents as well as create new documents for other languages such as SMIL and SVG. Links to these documents will be added in future versions of the WCAG 2.0 Working Draft.

Overview of Design Principles

Every Web site has been created because some person or group of people wanted to accomplish something - whether to provide the weather report for a community or to create a family photo album or to sell cars. The purpose and design of a site will vary as much as the people who create it. A site that is usable, attractive and meets the needs of its audience is designed that way. In the same manner, accessible Web site design is a conscious effort.

When these principles are ignored, individuals with disabilities may not be able to access the content at all, or they may be able to do so only with great difficulty. When these principles are employed, they also make Web content accessible to a variety of Web-enabled devices, such as phones, handheld devices, kiosks, network appliances, etc. By making content accessible to a variety of devices, the content is now accessible to people in a variety of situations.

Not all devices are the same. Not all systems are the same. Not all people are the same. Attempt to cater to the maximum number of people in the maximum number of scenarios. This can be achieved through a single accessible rendering or multiple accessible renderings optimized for different situations.

The four design principles in this document are:

  1. Presentation
  2. Interaction
  3. Comprehension
  4. Technology considerations

Note: These guidelines apply only to Web content presented to a human reader. A structured database or metadata collection where the data is intended for use by another machine and thus requires no interface lies outside the scope of these guidelines.

Presentation and Interaction

Have you ever adjusted the height of a chair because it was too low or too high? Have you ever adjusted the volume on a stereo? Have you ever used a magnifying glass to read small print?

We adjust objects in our environment to meet our needs. We use tools to help us do things we cannot do on our own. Both in real life and on the Web, some people rely on these adjustments to work, to contribute to society, and to enjoy life.

Here are a few scenarios, by no means an exhaustive list of the variations and types of disabilities and needs:

For more in-depth scenarios, please read "How People with Disabilities Use the Web".

A process for building content

Think about the process used to build a new office building. The structure of the building - its skeleton - is built before the decorations are added.

Similarly, the first place to start in your design is with the structure. How many chapters does your document have? Which navigation links are the most important and where should they go? What is the best way to express this idea - do I need an animated simulation to help people understand?

Once the structure is finished, the walls are painted and pictures are hung. On your web site, this is like deciding the color of chapter titles and how text will flow around images.

Steps and ladders

The architect designed the building with both elevators and stairs. Some people prefer to take stairs, while some people find the stairs too challenging or impossible. On your Web site, some people will prefer images, animations, multimedia, fast-paced interactive games, while others will find them too challenging or impossible to use. As with elevators and stairs, provide a variety of ways for people to access and to navigate through your Web content.


Have you ever traveled to a country where you cannot read any of the street signs? Have you ever had too many things to do and forgotten something important? Have you ever tried to learn a new, difficult concept but unable to find an explanation based on something you to understand?

The Web is an exciting new global space and it is easy to become disoriented. @@need help here

Technology considerations

Have you ever used a piece of plastic to make a purchase at a store? Have you ever been lost and wished you could ask your car for directions? Have you ever flipped a switch to turn on a light in your house and then been billed for the use of electricity at the end of the month?

We access networks of information through a variety of interfaces on a daily basis. Credit and check cards are tied to our bank accounts. Our bank accounts are tied to our billing addresses. The electricity in our home is attached to a meter, and with each flick of the switch the electric company gets information on our use.

The Web is just one way to transport that information. @@need help here.

Guideline 1 - Presentation.
Design content that allows presentation according to the user's needs and preferences

User needs and preferences are influenced by:

For more information about user capabilities, device capabilities, assistive technologies, and usage scenarios refer to the Working Draft "How People with Disabilities Use the Web."

1.1 Provide a text equivalent for all non-text content.


A text equivalent

Depending on the purpose and content of the non-text content, a short label may be appropriate, or a more thorough explanation may be required.

Non-text content includes images, text in raster images, image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video.


Text equivalents provide access to non-text information for someone who cannot see at all, who cannot see well, or who needs to supplement visual information with auditory information.

Success criteria

You will have successfully provided a text equivalent for all non-text content if:


1.2 Synchronize media equivalents with time-dependent presentations.


Multimedia presentations include both audio and video tracks. During the time that one of the tracks does not present any significant information, there is opportunity to include a synchronized equivalent.


Captions provide auditory information for people who are deaf or who have hearing loss. Audio descriptions provide visual information for people who are blind or who have low vision. Captions also provide auditory information for people who have lowered the sound volume or are in a noisy environment. Audio descriptions also provide visual information for people who are temporarily not looking at the video presentation, for example while following a video yoga program they are in a pose that causes them to look away from the screen

Success criteria

You will have successfully synchronized auditory and visual equivalents with multimedia if:


1.3 Use markup or a data model to provide the logical structure of content.


The logical structure of content represents changes in context. For example,

  1. A book is divided into chapters, paragraphs, lists, etc. Chapter titles help the reader anticipate the meaning of the following paragraphs. Lists clearly indicate separate, yet related ideas. An italicized phrase emphasizes an important idea. All of these divisions help the reader anticipate changes in context.
  2. A theatrical play is divided into scenes and acts. The curtain lowering, characters leaving the stage, or a short burst of music are a few ways to highlight changes in context during a play.
  3. A bicycle is divided into wheels and a frame. Further, a wheel is divided into a tire and a rim. In an image of the bicycle, one group of circles and lines becomes "wheel" while another group becomes "frame."

A data model is...


When the logical structure is documented in markup or a data model,

Success criteria


1.4 Identify the primary natural language of text and text equivalents and all changes in natural language.


Natural languages are those used by humans to communicate, including spoken, written, and signed languages.


Oftentimes, phrases from various languages are interspersed in writing. When these phrases are identified, a speech synthesizer can voice text with the appropriate accent and pronunciation. When they are not identified, the speech synthesizer will use the default accent and pronunciation dictionary. Identifying changes in language will also allow a tool to ask for automatic translations of that content. When editing documents, authoring tools can switch between appropriate spelling dictionaries.

Success criteria

Changes in language will be identified at the level the changes occur. If there is never a change throughout a whole site, then identification can occur at the highest level (usually at a page or document level). If changes occur at the word or phrase level, then changes should be identified at the word or phrase level using the markup appropriate to the markup language in use.


1.5 Separate content and structure from presentation.





Content and presentation can be separated because the rules that control how content is displayed can be separated from the markup that denotes the structure of the content.

Typically, style rules are stored separately from the content to which they apply, in resources which are referred to in these guidelines as style sheets. To facilitate the presentation of Web content by a range of devices (high and low-resolution displays, printers, speech devices, etc.), it is advisable to associate a variety of style sheets with your Web content.

Success criteria


2.1 Handle input errors, such as misspellings.


People with writing disabilities and people with dyslexia often have difficulty writing text in forms or other places that need text input. People with speech disabilities might not be recognized properly in voice input applications.

Success criteria

You will have successfully provided more than one path or method to find content if you:

2.2 Provide consistent and predictable responses to user actions.


Providing responses to user actions is important feedback for the user. This lets them know that your site is working properly and encourages them to keep interacting. When the user receives an unexpected response, they might think something is wrong or broken. Some people might get so confused they will not be able to use your site. Common responses to user actions:

These actions should be predictable and sensible to the end user. Make interactions consistent, both throughout the site and with commonly used interaction metaphors used throughout the Web.

Success criteria

You will have successfully provided consistent and predictable responses to user actions if you:


2.3 Give users control of mechanisms that cause extreme changes in context.


Mechanisms that cause extreme changes in context include:


If the user is unable to track visual cues that make extreme changes obvious, then they will not realize the context has changed. People who are blind, some people with low vision, some people with dyslexia and other people who have difficulty interpreting visual cues need guidance during extreme changes in context.

Success criteria

You will have successfully given users control of mechanisms that cause extreme changes in context if you:


2.4 Either give the user control over how long they can interact with content that requires a timed response or give them as much time as possible.


Examples of content that requires a timed response:


People with reading disabilities, cognitive disabilities, and learning disabilities often need longer than most people to read and comprehend written text. People with physical disabilities might not be able to move quickly or accurately enough to interact with moving objects. Content that is updated often might not be processed and read in time or in the proper order by a screen reader.

Success criteria

You will have successfully given the user adequate time to interact with content if you:


2.5 Use device-independent event handlers.


Device-independent access allows the user to interact with the content through a preferred device. For example, a mouse, a keyboard, a microphone, or a head wand. There are a variety of input devices that exist today and who knows what might be possible in the future. In general, if keyboard interaction is supported, speech input or a command line interface will also be supported.

Success criteria

You will have successfully used device-independent event handlers if you:

You will have successfully used device-independent event handlers if the user can interact with your application through the keyboard only or in conjunction with a mouse.


2.6 Avoid causing the screen to flicker.


People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights). Such users configure their user agents and system devices to avoid screen at rates that individually affect them.

Success criteria

You will have successfully avoided causing the screen to flicker if you:

Guideline 3. Comprehension:
Make it as easy as possible to use and understand

3.1 Use consistent presentation.


Presentation includes, but is not limited to:


Consistency helps users predict where to find information on each page of your site. It also helps users determine the relationships between items in the content. This understanding of the structure helps users navigate, orient themselves, and thus understand.

Note that differences in presentation also help users determine that they have succeeded in loading a new page. Differences also help users distinguish between content. Highlighting these differences is covered in the next checkpoint 3.2.

This checkpoint asks the author to make items with similar functions have a similar appearance or sound, while checkpoint 3.2 asks the author to highlight the differences through presentation.

Success criteria

You will have successfully used consistent presentation if you:

3.2 Emphasize structure through presentation, positioning, and labels.


Presentation that emphasizes structure enables users to be

If the default presentation of the structured content does not meet the needs of your audience use graphics, colors, sounds, and other aspects of presentation to emphasize the structure. However, ensure that the structural and semantic distinctions are captured in the markup.

Success criteria

You will have successfully emphasized structure through presentation, positioning, and labels if you:


3.3 Write as simple as possible yet appropriate for the site's content.


Authors should strive for clear and simple writing to aid all users, especially those with cognitive, learning, and/or reading disabilities. This should not discourage you from expressing complex or technical ideas. Using clear and simple language also benefits people whose first language differs from your own, including those people who communicate primarily in sign language.

Success criteria

You will have successfully made content clear and simple if you:


3.4 Supplement text with non-text content.


Non-text content is content that is not text, e.g. images, audio clips, videos, animations, etc.


Sounds, graphics, videos and animations can help make concepts presented in a Web site easier to understand, especially for people with cognitive, reading, or learning disabilities or those who are unfamiliar with the language of the text of the site.

"Designers need to be cautious in deciding when to use illustrations. Reading a picture is probably a learned activity that is easier for some than others. Some users skip the pictures; others read only the pictures. Designers must also recognize that visual conventions are not universal and that individuals develop their own mental schema and expectations in interpreting visual information.
For a detailed discussion of guidelines pertaining to illustrations, consult Tufte (1983) and MacDonald-Ross (1977)." Robert W. Bailey, Ph.D., Human Performance Engineering, 3rd edition. ]\pg 431.

Success criteria

3.5 Annotate complex or unfamiliar information with summaries and definitions.


Content is considered complex if the relationships between pieces of information are not easy to figure out. If the presentation of the information is intended to highlight trends or relationships between concepts, these should be explicitly stated in the summary.

Examples of complex information:

Content might be unfamiliar if you are using terms specific to a particular community, such as many of the terms used in this document are specific to the disability community.


Similar to illustrating written concepts with supplemental non-text content, annotating complex information with summaries helps people who do not read well to understand the content. It also helps people who are not able to pick up on visual cues between relationships of content.

Defining key terms and specialized language will help people who are not familiar with the topic you are presenting. Providing the expansion of abbreviations and acronyms not only helps people who are not familiar with the abbreviation or acronym but can clarify which meaning of an abbreviation or acronym is appropriate to use. For example, the acronym "ADA" stands for both the American with Disabilities Act as well as the American Dental Association.

Success criteria

You will have successfully annotated complex or unfamiliar information with summaries and definitions if you:

Guideline 4. Technology considerations:
Design for compatibility and interoperability

4.1 Choose technologies that support the use of these guidelines.


Markup languages, multimedia formats, software interface standards, etc., vary in their support of accessibility. When choosing which technologies to use, consider how easy it is apply these guidelines.

Success criteria

You will have successfully chosen a technology that supports the use of these guidelines if the technology:

Note: replace this with a summary of the XML Accessibility Guidelines once they are stable?

4.2 Use technologies according to specification.


When languages, API's, and protocols are used according to specification, tools that use the results will be able to do so as intended and expected.

Success criteria


4.3 Design user interfaces compatible with assistive technology.


Ensure that the user interface follows principles of accessible design: device-independent access to functionality, keyboard operability, self-voicing, etc. When an embedded object has its "own interface", the interface -- like the interface to the browser itself -- must be accessible. If the interface of the embedded object cannot be made accessible, an alternative accessible solution must be provided

Success criteria

You will have successfully designed an assistive-technology compatible user interface if you:

4.4 Design content so that when presentation effects are turned off or not supported the content is still usable.


Ensure that when stylistic or scripting technologies are not supported or turned off the content is still usable and readable by the user. This only applies to technologies that associate presentation with structure.

Success criteria

This may be accomplished by providing:

In determining the extent to which older technologies should be supported, keep in mind that

Appendix A: Glossary

Audio description

An audio description is either a prerecorded human voice or a synthesized voice that has either been prerecorded or is generated as the presentation plays. The audio description is synchronized with the audio track of the presentation, usually during natural pauses in the audio track. Audio descriptions include information about actions, body language, graphics, and scene changes.

Data model
Not yet defined.
Not yet defined.
Not yet defined.
Not yet defined. The definition must include the idea of timelines and slide shows (per 30 November 2000 telecon)
Throughout this document we refer to several "non-normative" examples. These are included to help readers understand concepts. Normative items are prescriptions for what must/should/may be done to create accessible content.
Not yet defined.
Not yet defined.
Transform gracefully
Not yet defined.

Appendix B: Contributors

Regular participants of the WCAG Working Group:

Kynn Bartlett, Paul Bohman, Jonathan Chetwynd, Wendy Chisholm, Al Gilman, Katie Haritos-Shea, Donovan Hipke, Thanasis Kinias, William Loughborough, Charles McCathieNevile, Matt May, Sean B. Palmer, Anne Pemberton, Adam Victor Reed, Loretta Guarino Reid, Emmanuelle Gutiérrez y Restrepo, Gregory J. Rosmaita, Lisa Seeman, Cynthia Shelly, Andi Snow-Weaver, Gregg Vanderheiden, Jason White

Other contributors:

Dan Aunspach, Bruce Bailey, Harvey Bingham, Judy Brewer, Dan Brickley, Dick Brown, David Clark, Michael Cooper, Nir Dagan, Daniel Dardailler, Alan J. Flavell, Geoff Freed, Greg Gay, Jon Gunderson, Shawn Lawton Henry, Chuck Hitchcock, Ian Jacobs, Marshall Jansen, Phill Jenkins, Leonard Kasday, Chris Kreussling, Chuck Letourneau, Greg Lowney, Scott Luebking, Lisa Kestenbaum, Marja-Riitta Koivunen, Marti McCuller, Masafumi NAKANE, Robert Neff, Tim Noonan, Anuska Perkins, David Poehlman, Chris Ridpath, Greg Rosenberg, Heather Swayne, David Tanner, Jim Thatcher, Claus Thøgersen, Peter Verhoeven, Cynthia Waddell, Mike Williams

Appendix C: The differences between WCAG 1.0 and WCAG 2.0

Since the release of WCAG 1.0 in May 1999, the WCAG Working Group has received feedback on priorities of checkpoints, the usability of the set of documents, and requests for clarifications on the meaning of specific checkpoints and what is needed to satisfy them. Thus, it is intended that WCAG 2.0:

For a checkpoint by checkpoint comparison, refer to the Checkpoint Mapping Between WCAG 1.0 and WCAG 2.0 Working Draft.

Improvements in WCAG 2.0

We hope that WCAG 2.0 will have several improvements over WCAG 1.0.

More easily used with a wide range of languages
When WCAG 1.0 was written, most of the Web used HTML. The guidelines were designed with that in mind, and applying the guidelines to other languages has identified some areas that can be improved. The new version should be easier to apply to a wider range of languages and content types.
More easily used by authoring tool developers
The Authoring Tool Accessibility Guidelines rely heavily on WCAG to define how to make Web content accessible. Simplifying the guidelines will improve their usability for this important group.
Easier to determine conformance
In WCAG 1.0 there were a number of checkpoints that began "until user agents...". In the new version there are no such checkpoints. This reduces the confusion as to when a checkpoint has been met as well as the resource commitment required to keep the information produced up to date.