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This document provides an introduction to use of the Web by people with disabilities. It illustrates some of their requirements when using Web sites and Web-based applications, and provides supporting information for the guidelines and technical work of the World Wide Web Consortium's (W3C) Web Accessibility Initiative (WAI). It is not a comprehensive or in-depth discussion of disabilities, nor of the assistive technologies used by people with disabilities.
This document version is a W3C Working Draft intended for eventual publishing as a W3C Note. It may be superseded by a later version maintained at the W3C. This document is issued by the Education and Outreach Working Group (EOWG) as part of the WAI International Program Office Activity. Comments from the public, W3C Members, and working groups are welcome at email@example.com. A list of current W3C technical reports and publications including working drafts and notes can be found at http://www.w3.org/TR/.
The Web Accessibility Initiative (WAI) develops guidelines for accessibility of Web sites, browsers, and authoring tools, in order to make it easier for people with disabilities to use the Web. Given the Web's increasingly important role in society, access to the Web is vital for people with disabilities. Many of the accessibility solutions described in WAI materials also benefit Web users who do not have disabilities.
This document provides a general introduction to how people with different kinds of disabilities use the Web. It provides background to help understand how people with disabilities benefit from provisions described in the Web Content Accessibility Guidelines 1.0, Authoring Tool Accessibility Guidelines 1.0, and User Agent Accessibility Guidelines 1.0. Specifically, this document describes:
The following examples show people with a variety of disabilities using various assistive technologies or adaptive strategies to access the Web. These scenarios do not represent actual individuals. The particular combinations of assistive technologies, and individuals' expertise in using those technologies, should not be presumed for everyone with similar disabilities as those portrayed. In some cases, browsers, multimedia players, or assistive technologies with specific features supporting accessibility may not yet be available in an individual's primary language.
Each scenario contains links to additional information on the specific disability or disabilities described in more detail in Section 3; to the assistive technology or adaptive strategy described in Section 4; and to detailed curriculum examples or guideline checkpoints in the Scenarios References in Section 6.
The following examples highlight use of some accessibility accommodations:
Mr. Lee is in the market for some new clothes, appliances, and music. As he frequently does, he is spending a weeknight evening shopping online. He has one of the most common visual disabilities for men: color blindness, which in his case means an inability to distinguish between green and red.
He has difficulty reading the text on many Web sites. When he first starting using the Web, he had thought that a lot of sites used poor color contrast, since to him many sites seemed to use similar shades of brown. He eventually realized that many sites were using color combinations that were indistinguishable to him because of his red/green color blindness.
After additional experimentation, Mr. Lee discovered that on some sites, the colors were controlled by style sheets and that he could override these with his own style sheets in his browser; but that other sites did not use style sheets and sometimes he could not override those. As he continued to experiment with turning style sheets on or off, he realized that on some sites the sale prices were indicated in red text, which only became visible for him when he turned off the sites' style sheets -- when possible on those sites -- and used his own.
After a half hour of browsing, Mr. Lee makes a number of online purchases. Because of increased readability, he buys mainly from Web sites where he can use his own style sheets.
Mr. Jones is a reporter who must submit his articles in HTML for publishing in an on-line journal. Over his twenty-year career, he has developed repetitive stress injury (RSI) in his hands and arms, and it has become painful for him to type. He uses a combination of speech recognition and an alternative keyboard to prepare his articles, but he doesn't use a mouse. It took him several months to become sufficiently accustomed to using speech recognition to be comfortable working for many hours at a time. There are some things he has not worked out yet, such as a sound card conflict that arises whenever he tries to use speech recognition on Web sites that have streaming audio.
He has not been able to use the same Web authoring software as his colleagues, because the application that his office chose for a standard is missing many of the keyboard equivalents that he needs in place of mouse-driven commands. To activate commands that do not have keyboard equivalents, he would have to use a mouse instead of speech recognition or typing, and this would re-damage his hands at this time. He researched some of the newer versions of authoring tools and selected one with full keyboard support. Within a month, he discovered that several of his colleagues have switched to the new product as well, after they found that the full keyboard support was easier on their own hands.
When browsing other Web sites to research some of his articles, Mr. Jones likes the access key feature that is implemented on some Web pages. It enables him to shortcut a long list of links that he would ordinarily have to tab through by voice, and instead go straight to the link he wants.
Ms. Martinez is taking several distance learning courses in physics. She is deaf. She had little trouble with the curriculum until the university upgraded their on-line courseware to a multimedia approach, using an extensive collection of audio lectures. For classroom-based lectures the university provided interpreters; however for Web-based instruction they initially did not realize that accessibility was an issue, then said they had no idea how to provide the material in accessible format. She was able to point out that the University was clearly covered by a policy requiring accessibility of online instructional material, and then to point to the Web Content Accessibility Guidelines 1.0 as a resource providing guidance on how to make Web sites, including those with multimedia, accessible.
The University had the lectures transcribed and made this information available through their Web site along with audio versions of the lectures. For an introductory multimedia piece, the university used a SMIL-based multimedia format enabling synchronized captioning of audio and description of video. The school's information managers quickly found that it was much easier to comprehensively index the audio resources on the accessible area of the Web site, once these resources were captioned with text.
The professor for the course also set up a chat area on the Web site where students could exchange ideas about their coursework. Although she was the only deaf student in the class and only one other student knew any sign language, she quickly found that the Web-based chat format, and the opportunity to provide Web-based text comments on classmates' work, ensured that she could keep up with class progress.
Ms. Laitinen is an accountant at an insurance company that uses Web-based formats over a corporate intranet. She is blind. She uses a screen reader to interpret what is displayed on the screen and generate a combination of speech output and refreshable braille output. She uses the speech output, combined with tabbing through the navigation links on a page, for rapid scanning of a document, and has become accustomed to listening to speech output at a speed that her co-workers cannot understand at all. She uses refreshable braille output to check the exact wording of text, since braille enables her to read the language on a page more precisely.
Much of the information on the Web documents used at her company is in tables, which can sometimes be difficult for non-visual users to read. However, since the tables on this company's documents are marked up clearly with column and row headers which her screen reader can access, she easily orients herself to the information in the tables. Since the insurance codes she must frequently reference include a number of abbreviations and acronyms, she finds the expansions of abbreviations and acronyms the first time they appear on a page allows her to better catch the meaning of the short versions of these terms.
As one of the more senior members of the accounting staff, Ms. Laitenen must frequently help newer employees with their questions. She has recently upgraded to a browser that allows better synchronization of the screen display with audio and braille rendering of that information. This enables her to better help her colleagues, since the screen shows her colleagues the same part of the document that she is reading with speech or braille output.
Ms. Olsen attends middle school, and particularly likes her literature class. She has attention deficit disorder with dyslexia, and the combination leads to substantial difficulty reading. However with recent accommodations to the curriculum she has become enthusiastic about this class.
Her school has started to use more online curricula to supplement class textbooks. She was initially worried about reading load, since she reads slowly. But recently she tried text to speech software, and found that she was able to read along visually with the text much more easily when she could hear certain sections of it read to her with the speech synthesis, instead of struggling over every word.
Her class' recent area of focus is Hans Christian Andersen's writings, and she has to do some research about the author. When she goes onto the Web, she finds that some sites are much easier for her to use than others. Some of the pages have a lot of graphics, and those help her focus in quickly on sections she wants to read. In some cases, though, where the graphics are animated, it is very hard for her to focus, and so it helps to be able to freeze the animated graphics -- [and then explain that without the alt text it's harder to know the content]
One of the most important things for her has been the level of accessibility of the Web-based online library catalogues and the general search functions on the Web. Sometimes the search options are confusing for her. Her teacher has taught a number of different search strategies, and she finds that some sites provide options for a variety of searching strategies and she can more easily select searching options that work well for her.
[@@review/expand detail] He customized his portfolio window to give a streamlined portfolio view, and to automatically check certain stock performance criteria since he has difficulty remembering how to find the information otherwise. He uses his browser settings to enlarge the font on the site so it is easier for him to see. While the icons on the site do not enlarge along with the fonts, they are large enough already that he can not only see them easily, but can select them with the mouse even when his hand is trembling. maybe some importance w/ online shopping and banking... grocery shopping for convenience... show someone at home, bringing services to themselves
Ms. Smith uses the Web to find new restaurants to go to with friends and colleagues. She has low vision and is deaf. She uses a screen magnifier to enlarge the text on Web sites until she can read it, but sometimes that isn't sufficient so she also uses a screen reader to drive a refreshable braille display, which she reads slowly. When she is using the screen magnifier, she also uses her browser settings to turn off background color and patterns because otherwise there is not enough contrast for her.
[@@review/expand detail] The city Ms. Smith lives in has compiled a multi-media virtual tour of entertainment options in the area, and Ms. Smith discovers it has been completely captioned and described. She takes the on-line tour, slowing it down a few times while she uses a combination of braille and screen magnification. Then she sends the URI of the virtual tour to friends, to see if they share her interest in trying a particularly good-looking new restaurant downtown that weekend.
talk about sample menus, online. all her settings for display should be dealt with in the screen magnifier not in the browser. can we talk about her accessing this info from a mobile setting, e.g. perhaps w/ a braillelite connected via infrared to a mobile phone that can access the Web (check this w/ Gregg). OR better yet, she takes her braillelite up to a Web-based public info kiosk in a mall, and links up via infrared. describe how she synchs up her machine... with the kiosk, and then checks sample menus. also mention at home use of screen reader and contrast with braille lite on the road. emphasize back in blindness section that blindness is not necessarily absolute. change 'particularly good-looking" to appealing ///download the menu into her braillelite...
[She is in Brussels but speaks Spanish? & wants to read the Web site in her own languge]
///looking for transportation/// on the Web///
Mr. Sands has bagged groceries for the past year at an online grocery service. He has Down syndrome, and has difficulty with abstract concepts. He has difficulty reading and doing mathematical calculations.
Recently, he visited the customer Web site for the grocery service from his computer at home. He found that he could use the Web site without much difficulty -- it used a lot of pictures, and each Web page was clearly organized. Some of the products had audio descriptions available also. When he clicked on an icon showing a product, it sent his choice directly to an order form.
Back at work, the company's Web developer was interviewing clerks in preparation for updating the online clerk interface. Mr. Sands found an opportunity to mention to the Web developer that the customer Web site was convenient for him, and better than some other online grocery services that he'd looked at. He showed the Web developer that the clear and simple language [14.1] and consistent design [14.3] and navigation options [13.4] on the customer site, as well as the availability of both text and audio [14.2], helped him use the site. The other clerks thought that the icons might allow them to identify and select products faster than text alone.
The Web developer decided to implement WCAG 1.0 in the online clerk interface. Mr. Sands' job options have since changed at the online grocery service. He now checks orders after they are filled. When an order displays on the screen, it displays as product icons with text. He can select an audio description when he needs to. If an item is missing from the bagged order, he selects the icon which sends a message to a bagging clerk who fills the order.
This section describes general kinds of disabilities that can affect access to the Web. There are as yet no universally accepted categorizations of disability, despite efforts towards that goal. Commonly used disability terminology varies from country to country and between different disability communities in the same country. There is a trend in many disability communities to use functional terminology instead of medical classifications. This document does not attempt to comprehensively address issues of terminology.
Abilities can vary from person to person, and over time, for different people with the same type of disability. People can have combinations of different disabilities, and combinations of varying levels of severity.
The term "disability" is used very generally in this document. Some people with conditions described below would not consider themselves to have disabilities. They may, however, have limitations of sensory, physical or cognitive functioning which can affect access to the Web. These may include injury-related and aging-related conditions, and can be temporary or chronic.
The number and severity of limitations tend to increase as people age, and may include changes in vision, hearing, memory, or motor function. Aging-related conditions can be accommodated on the Web by the same accessibility solutions used to accommodate people with disabilities.
Sometimes different disabilities require similar accommodations. For instance, someone who is blind and someone who cannot use his or her hands both require full keyboard equivalents for mouse commands in browsers and authoring tools, since they both have difficulty using a mouse but can use assistive technologies to activate commands supported by a standard keyboard interface.
Many accessibility solutions described in this document contribute to "universal design" (also called "design for all") by benefiting non-disabled users as well as people with disabilities. For example, support for speech output not only benefits blind users, but also Web users whose eyes are busy with other tasks; while captions for audio not only benefit deaf users, but also increase the efficiency of indexing and searching for audio content on Web sites.
Each description of a general type of disability includes several brief examples of the kinds of barriers someone with that disability might encounter on the Web. These lists of barriers are illustrative and not intended to be comprehensive. Barrier examples listed here are representative of accessibility issues that are relatively easy to address with existing accessibility solutions, except where otherwise noted.
Blindness involves a substantial, uncorrectable loss of vision in both eyes.
To access the Web, many individuals who are blind rely on screen readers -- software that reads text on the screen (monitor) and outputs this information to a speech synthesizer and/or refreshable braille display. Some people who are blind use text-based browsers such as Lynx, or voice browsers, instead of a graphical user interface browser plus screen reader. They may use rapid navigation strategies such as tabbing through the headings or links on Web pages rather than reading every word on the page in sequence.
Examples of barriers that people with blindness may encounter on the Web include:
There are many types of low vision (also known as "partially sighted" in
parts of Europe), for instance poor acuity (vision that is not sharp), tunnel
vision (seeing only the middle of the visual field), central field loss (seeing
only the edges of the visual field), and clouded vision.
To use the Web, some people with low vision use extra-large monitors, and increase the size of system fonts and images. Others use screen magnifiers or screen enhancement software. Some individuals use specific combinations of text and background colors, such as a 24-point bright yellow font on a black background, or choose certain typefaces that are especially legible for their particular vision requirements.
Barriers that people with low vision may encounter on the Web include:
Color blindness is a lack of sensitivity to certain colors. Common forms
of color blindness include difficulty distinguishing between red and green,
or between yellow and blue. Sometimes color blindness results in the inability
to perceive any color.
To use the Web, some people with color blindness use their own style sheets to override the font and background color choices of the author.
Barriers that people with color blindness may encounter on the Web include:
Deafness involves a substantial uncorrectable impairment of hearing in both
ears. Some deaf individuals' first language is a sign language, and they
may or may not read or speak a language fluently.
To use the Web, many people who are deaf rely on captions for audio content. They may need to toggle the captions on an audio file on or off as they browse a page.
Barriers that people who are deaf may encounter on the Web include:
A person with a mild to moderate hearing impairment may be considered hard
To use the Web, people who are hard of hearing may rely on captions for audio content and/or amplification of audio. They may need to toggle the captions on an audio file on or off, or adjust the volume of an audio file.
Barriers encountered on the Web include:
Motor disabilities can include weakness, limitations of muscular control
(such as involuntary movements, lack of coordination, or paralysis), limitations
of sensation, joint problems, or missing limbs. Some physical disabilities
can include pain that impedes movement. These conditions can affect the hands
and arms as well as other parts of the body.
To use the Web, people with motor disabilities affecting the hands or arms may use a specialized mouse; a keyboard with a layout of keys that matches their range of hand motion; a pointing device such as a head-mouse, head-pointer or mouth-stick; voice-recognition software; an eye-gaze system; or other assistive technologies to access and interact with the information on Web sites. They may activate commands by typing single keystrokes in sequence with a head pointer rather than typing simultaneous keystrokes ("chording") to activate commands. They may need more time when filling out interactive forms on Web sites if they have to concentrate or maneuver carefully to select each keystroke.
Barriers that people with motor disabilities affecting the hands or arms may encounter include:
Speech disabilities can include difficulty producing speech that is recognizable
by some voice recognition software, either in terms of loudness or clarity.
To use parts of the Web that rely on voice recognition, someone with a speech disability needs to be able to use an alternate input mode such as text entered via a keyboard.
Barriers that people with speech disabilities encounter on the Web include:
Individuals with dyslexia or dyscalculia (sometimes called "learning
disabilities" in the U.S.) may have difficulty processing written language
or images when read visually, or spoken language when heard, or numbers when
read visually or heard.
To use the Web, people with learning disabilities may rely on getting information through several modalities at the same time. For instance, someone who has difficulty reading may use a screen reader plus synthesized speech to facilitate comprehension, while someone with an auditory processing disability may use captions to help understand an audio track.
Barriers that people with learning disabilities may encounter on the Web include:
Individuals with attention deficit disorder may have difficulty focusing on information.
To use the Web, an individual with an attention deficit disorder may need to turn off animations on a site in order to be able to focus on the site's content.
Barriers that people with attention deficit disorder may encounter on the Web include:
Individuals with impairments of intelligence (sometimes called "learning
disabilities" in Europe) may learn more slowly, or have difficulty understanding
To use the Web, people with impairments of intelligence may take more time on a Web site, may rely more on graphics to enhance understanding of a site, and may benefit from the level of language on a site not being unnecessarily complex for the site's intended purpose.
Individuals with memory impairments may have problems with short-term memory,
missing long-term memory, or some loss of language.
To use the Web, people with memory impairments may rely on a consistent navigational structure throughout the site.
Individuals with mental or emotional disabilities may have difficulty focusing
on information on a Web site, or difficulty with blurred vision or hand tremors
due to side effects from medications.
To use the Web, people with psychiatric disabilities may need to turn off distracting visual or audio elements, or to use screen magnifiers.
Some individuals with seizure disorders are triggered by visual flickering
or audio signals at a certain frequency.
To use the Web, people with seizure disorders may need to turn off animations, blinking text, or certain frequencies of audio. Avoidance of these visual or audio frequencies in Web sites prevents inadvertent triggering of seizures.
Combinations of disabilities may reduce a user's flexibility in using accessibility information.
For instance, while someone who is blind can benefit from hearing an audio description of a Web-based video, and someone who is deaf can benefit from seeing the captions accompanying audio, someone who is both deaf and blind needs access to a text transcipt of the description of the audio and video, which they could access on a refreshable braille display.
Similarly, someone who is deaf and has low vision might benefit from the captions on audio files, but only if the captions could be enlarged and the color contrast adjusted.
Someone who cannot move his or her hands, and also cannot see the screen well, might use a combination of speech input and speech output, and might therefore need to rely on precise indicators of location and navigation options in a document.
Changes in people's functional ability due to aging can include subtle and/or gradual changes in abilities or a combination of abilities including vision, hearing, dexterity and memory. Barriers can include any of the issues already mentioned above. Any one of these limitations can affect an individual's ability to access Web content. Together, these changes can become more complex to accommodate.
For example, someone with low vision may need screen magnification, however when using screen magnification the user loses surrounding contextual information, which adds to the difficulty which a user with short-term memory loss might experience on a Web site.
Assistive technologies are products used by people with disabilities to help accomplish tasks that they cannot accomplish otherwise or could not do easily otherwise. When used with computers, assistive technologies are also refered to as adaptive software. Some assistive technologies rely on output of other user agents, such as graphical desktop browsers, text browsers, voice browsers, multimedia players, plug-ins. Adaptive strategies may be techniques that people with disabilities use, with or without assistive technologies, to assist in navigating Web pages. This is not a comprehensive list.
Alternate keyboards or switches are hardware or software devices used by people with physical disabilities, that provide an alternate way of creating keystrokes that appear to come from the standard keyboard. Examples include keyboard with extra-small or extra-large key spacing, keyguards that only allow pressing one key at a time, on-screen keyboards, eyegaze keyboards, and sip-and-puff switches. Web-based applications that can be operated entirely from the keyboard, with no mouse required, support a wide range of alternative modes of input.
Braille is a system using six to eight raised dots in various patterns to represent letters and numbers that can be read by the fingertips. Braille systems vary greatly around the world. Some "grades" of braille include additional codes beyond standard alpha-numeric characters to represent common letter groupings (e.g., "th," "ble" in Grade II American English braille) in order to make braille more compact. An 8-dot version of braille has been developed to allow all ASCII characters to be represented. Dynamic or refreshable braille involves the use of a mechanical display where dots (pins) can be raised and lowered dynamically to allow any braille characters to be displayed.
Screen magnification is software used primarily by individuals with low vision that magnifies a portion of the screen for easier viewing. At the same time screen magnifiers make presentations larger, they also reduce the area of the document that may be viewed, removing surrounding context . Some screen magnifiers offer two views of the screen: one magnified and one default size for navigation.
Sound notification is an alternative feature of some Web-based applications that allows deaf or hard of hearing users to receive visual notification that a warning or error sound has been emitted by the computer.
Software used by individuals who are blind or who have dyslexia that interprets what is displayed on a screen and directs it either to speech synthesis for audio output, or to refreshable braille for tactile output. Some screen readers use the document tree (i.e., the parsed document code) as their input. Older screen readers make use of the rendered version of a document, so that document order or structure may be lost (e.g., when tables are used for layout) and their output may be confusing.
Speech (or voice) recognition is used by people with some physical disabilities or temporary injuries to hands and forearms as an input method in some voice browsers. Applications that have full keyboard support can be used with speech recognition.
Scanning software is adaptive software used by individuals with some physical or cognitive disabilities that highlights or announces selection choices (e.g., menu items, links, phrases) one at a time. A user selects a desired item by hitting a switch when the desired item is highlighted or announced.
Speech synthesis or speech output can be generated by screen readers or voice browsers, and involves production of digitized speech from text. People who are used to using speech output sometimes listen to it at very rapid speeds.
[explain as adaptive strategy for people who can't scan visually or move the cursor over a screen with a mouse]
The World Wide Web is full of information about disabilities. The key can be locating information that is relevant to the issue of accessibility to the Web, accurate, and up-to-date. It can be important to note the perspective from which the information is written. For example, there is much information about different diseases on the Web, but medical details can be less relevant to understanding how people with disabilities use the Web than the perspectives of people with disabilities themselves, as well as that of organizations that focus on accessibility strategies for using information technologies and telecommunications.
W3C's Web Accessibility Initiative (WAI) addresses accessibility of the Web through five complementary activities that:
WAI's International Program Office enables partnering of industry, disability organizations, accessibility research organizations, and governments interested in creating an accessible Web. WAI sponsors include the US National Science Foundation and Department of Education's National Institute on Disability and Rehabilitation Research; the European Commission's DG XIII Telematics Applications Programme for Disabled and Elderly; Government of Canada, Industry Canada; IBM, Lotus Development Corporation, Microsoft, and Verizon. Additional information on WAI is available at http://www.w3.org/WAI.
The W3C was created to lead the Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. It is an international industry consortium jointly run by the Laboratory for Computer Science (LCS) at Massachusetts Institute of Technology (MIT) in the USA, the National Institute for Research in Computer Science and Control (INRIA) in France and Keio University in Japan. Services provided by the Consortium include: a repository of information about the World Wide Web for developers and users; reference code implementations to embody and promote standards; and various prototype and sample applications to demonstrate use of new technology. As of October 2000, over 450 organizations are Members of the Consortium. For more information about the World Wide Web Consortium, see http://www.w3.org/.
This section includes a variety of illustrative links for specific accessibility provisions highlighted in the scenarios section above. Some links lead to checkpoints in the Web Content Accessibility Guidelines 1.0, Authoring Tool Accessibility Guidelines 1.0, or User Agent Accessibility Guidelines 1.0. Other links lead to examples in the Curriculum for Web Content Accessibility Guidelines. It is not a comprehensive listing of accessibility provisions in the three WAI guidelines.
Using clear and consistent navigation mechanisms (from "clerk")
clear and simple language (from "clerk")
supplemental graphic and auditory representation of text (from "clerk")
consistent style of presentation across pages (from "clerk")
[@@ review, expand]
We would like to thank the following people who have contributed substantially to this document:
Ian Jacobs, Gregg Vanderheiden, Kate Vanderheiden, and Members of the Education and Outreach Working Group, including Kathleen Anderson (State of Connecticut, Office of the State Comptroller), Harvey Bingham, Helle Bjarnø (Videncenter for Synshandicap / Visual Impairment Information Centre), Alan Cantor (Cantor + Associates, Workplace Accommodation Consultants), Dave Clark, Libby Cohen (University of Southern Maine), Julie Howell (Royal National Institute for the Blind), Marja-Riitta Koivunen (W3C and Elisa Communications), Chuck Letourneau (Starling Access Services), William Loughborough (Smith-Kettlewell Institute), Charles McCathieNevile (W3C), Sheela Sethuraman (Center for Applied Special Technology), Henk Snetselaar (Bartimeus Educational Institute for the Blind and Partially Sighted), Jeff Turner (John Hancock Insurance Company), Carlos Velasco (German National Research Center for Information Technology), Eric Velleman (Bartimeus Educational Institute for the Blind and Partially Sighted).