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[contents]
W3C

How People with Disabilities Use the Web

Working-Group Internal Draft, 5 May 2005

This Version:
http://www.w3.org/WAI/EO/Drafts/PWD-Use-Web/20050505
Latest Version:
http://www.w3.org/WAI/intro/people-use-web/
Previous Version:
http://www.w3.org/WAI/EO/Drafts/PWD-Use-Web/20040708
Editors:
Judy Brewer (jbrewer@w3.org)
See also Acknowledgements section

Copyright © 1994-2005 W3C (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.

Abstract

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).

Status of this document

This document version is a Working-Group Internal 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 It may be superseded by a later version maintained at the W3C.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 wai-eo-editors@w3.org. A list of current W3C technical reports and publications including working drafts and notes can be found at http://www.w3.org/TR/.

Table of Contents

  1. Introduction
  2. Scenarios of People with Disabilities Using the Web
  3. Different Disabilities That Can Affect Web Accessibility
  4. Assistive Technologies and Adaptive Strategies
  5. Further Reading
  6. Scenario References
  7. General References
  8. Acknowledgements

1. Introduction

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. It is not a comprehensive or in-depth discussion of disabilities, nor of the assistive technologies used by people with disabilities. Specifically, this document describes:

This document contains many internal hypertext links between the sections on scenarios, disability requirements, assistive technologies, and scenario references. The scenario references and general references sections also include links to external documents.

2. Scenarios of People with Disabilities Using the Web

The following scenarios show people with different kinds of disabilities using assistive technologies and adaptive strategies to access the Web. In some cases the scenarios show how the Web can make some tasks easier for people with disabilities.

Please note that the scenarios do not represent actual individuals, but rather individuals engaging in activities that are possible using today's Web technologies and assistive technologies. The reader should not assume that everyone with a similar disability to those portrayed will use the same assistive technologies or have the same level of expertise in using those technologies. In some cases, browsers, media players, or assistive technologies with specific features supporting accessibility may not yet be available in an individual's primary language. Disability terminology varies from one country to another, as do educational and employment opportunities.

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.

Following is a list of scenarios and accessibility solutions:

Online shopper with color blindness

Mr. Lee wants to buy some new clothes, appliances, and music. As he frequently does, he is spending an 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, it seemed to him the text and images on a lot of sites used poor color contrast, since they appeared to use similar shades of brown. He realized that many sites were using colors that were indistinguishable to him because of his red/green color blindness. In some cases the site instructions explained that discounted prices were indicated by red text, but all of the text looked brown to him. In other cases, the required fields on forms were indicated by red text, but again he could not tell which fields had red text.

Mr. Lee found that he prefered sites that used sufficient color contrast, and redundant information for color. The sites did this by including names of the colors of clothing as well as showing a sample of the color; and by placing an asterix (*) in front of the required fields in addition to indicated them by color.

After additional experimentation, Mr. Lee discovered that on most newer sites the colors were controlled by style sheets and that he could turn these style sheets off with his browser or override them with his own style sheets. But on sites that did not use style sheets he couldn't override the colors. 

Eventually Mr. Lee bookmarked a series of online shopping sites where he could get reliable information on product colors, and not have to guess at which items were discounted. 

Reporter with repetitive stress injury

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.

Online student who is deaf

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.

Accountant with blindness

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. Her screen reader reads her the alternative text for any images on the site. 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.

Classroom student with dyslexia

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 recently 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 classes 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.

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.

Retiree with several aging-related conditions, managing personal finances

Mr. Yunus uses the Web to manage some of his household services and finances. He has some central-field vision loss, hand tremor, and a little short-term memory loss.

He uses a screen magnifier to help with his vision and his hand tremor; when the icons and links on Web pages are bigger, it's easier for him to select them, and so he finds it easier to use pages with style sheets. When he first started using some of the financial pages, he found the scrolling stocktickers distracting, and they moved too fast for him to read. In addition, sometimes the pages would update before he had finished reading them. Therefore he tends to use Web sites that do not have a lot of movement in the text, and that do not auto-refresh. He also tended to "get stuck" on some pages, finding that he could not back up, on some sites where new browser windows would pop open without notifying him.

Mr. Yunus has gradually found some sites that work well for him, and developed a customized profile at some banking, grocery, and clothing sites.

Supermarket assistant with cognitive disability

Mr. Sands has put groceries in bags for customers for the past year at a supermarket. He has Down syndrome, and has difficulty with abstract concepts, reading, and doing mathematical calculations. He usually buys his own groceries at this supermarket, but sometimes finds that there are so many product choices that he becomes confused, and he finds it difficult to keep track of how much he is spending. He has difficulty re-learning where his favorite products are each time the supermarket changes the layout of its products.

Recently, he visited an online grocery service from his computer at home. He explored the site the first few times with a friend. He found that he could use the Web site without much difficulty -- it had a lot of pictures, which were helpful in navigating around the site, and in recognizing his favorite brands.

His friend showed him different search options that were available on the site, making it easier for him to find items. He can search by brand name or by pictures, but he mostly uses the option that lets him select from a list of products that he has ordered in the past. Once he decides what he wants to buy, he selects the item and puts it into his virtual shopping basket. The Web site gives him an updated total each time he adds an item, helping him make sure that he does not overspend his budget.

The marketing department of the online grocery wanted their Web site to have a high degree of usability in order to be competitive with other online stores. They used consistent design and consistent navigation options so that their customers could learn and remember their way around the Web site. They also used the clearest and simplest language appropriate for the site's content so that their customers could quickly understand the material.

While these features made the site more usable for all of the online-grocery's customers, they made it possible for Mr. Sands to use the site. Mr. Sands now shops on the online grocery site a few times a month, and just buys a few fresh items each day at the supermarket where he works.

Teenager with deaf-blindness, seeking entertainment

Ms. Kaseem uses the Web to find new restaurants to go to with friends and classmates. She has low vision and is deaf. She uses a screen magnifier to enlarge the text on Web sites to a font size that she can read. When screen magnification is not sufficient, she also uses a screen reader to drive a refreshable braille display, which she reads slowly.

At home, Ms. Kaseem browses local Web sites for new and different restaurants. She uses a personal style sheet with her browser, which makes all Web pages display according to her preferences. Her preferences include having background patterns turned off so that there is enough contrast for her when she uses screen magnification. This is especially helpful when she reads on-line sample menus of appealing restaurants.

A multimedia virtual tour of local entertainment options was recently added to the Web site of the city in which Ms. Kaseem lives. The tour is captioned and described -- including text subtitles for the audio, and descriptions of the video -- which allows her to access it using a combination of screen magnification and braille. The interface used for the virtual tour is accessible no matter what kind of assistive technology she is using -- screen magnification, her screen reader with refreshable braille, or her portable braille device. Ms. Kaseem forwards the Web site address to friends and asks if they are interested in going with her to some of the restaurants featured on the tour.

She also checks the public transportation sites to find local train or bus stops near the restaurants. The Web site for the bus schedule has frames without meaningful titles, and tables without clear column or row headers, so she often gets lost on the site when trying to find the information she needs. The Web site for the local train schedule, however, is easy to use because the frames on that Web site have meaningful titles, and the schedules, which are laid out as long tables with clear row and column headers that she uses to orient herself even when she has magnified the screen display. 

Occasionally she also uses her portable braille device, with an infrared connection, to get additional information and directions at a publicly-available information kiosk in a shopping mall downtown; and a few times she has downloaded sample menus into her braille device so that she has them in an accessible format once she is in the restaurant.

3. Different Disabilities that Can Affect Web Accessibility

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.

Following is a list of some disabilities and their relation to accessibility issues on the Web.

Visual disabilities

Blindness (scenario -- "accountant")

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 can include:

Low vision (scenarios -- "teenager" and "retiree")

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 can include:

Color blindness (scenario -- "shopper")

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 can include:

Hearing Impairments

Deafness (scenario -- "online student")

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 a written language fluently, or speak clearly.

To use the Web, many people who are deaf rely on captions for audio content. They may need to turn on the captions on an audio file as they browse a page; concentrate harder to read what is on a page; or rely on supplemental images to highlight context.

Barriers that people who are deaf may encounter on the Web can include:

Hard of hearing

A person with a mild to moderate hearing impairment may be considered hard of hearing.

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 can include:

Physical disabilities

Motor disabilities (scenario -- "reporter")

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

Speech disabilities

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 can include:

Cognitive and neurological disabilities

Visual and Auditory Perception (scenario -- "classroom student")

Individuals with visual and auditory perceptual disabilities, including dyslexia (sometimes called "learning disabilities" in Australia, Canada, the U.S., and some other countries) and dyscalculia may have difficulty processing language or numbers. They may have difficulty processing spoken language when heard ("auditory perceptual disabilities"). They may also have difficulty with spatial orientation.

To use the Web, people with visual and auditory perceptual 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 visual and auditory perceptual disabilities may encounter on the Web can include:

Attention deficit disorder (scenario -- "classroom student")

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 can include:

Intellectual disabilities (scenario -- "supermarket assistant")

Individuals with impairments of intelligence (sometimes called "learning disabilities" in Europe; or "developmental disabilities" or previously "mental retardation" in the United States) may learn more slowly, or have difficulty understanding complex concepts. Down Syndrome is one among many different causes of intellectual disabilities.

To use the Web, people with intellectual disabilities 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.

Barriers can include:

Memory impairments (scenario -- "retiree")

Individuals with memory impairments may have problems with short-term memory, missing long-term memory, or may have some loss of ability to recall language.

To use the Web, people with memory impairments may rely on a consistent navigational structure throughout the site.

Barriers can include:

Mental health disabilities

Individuals with mental health 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 mental health disabilities may need to turn off distracting visual or audio elements, or to use screen magnifiers.

Barriers can include:

Seizure disorders

Some individuals with seizure disorders, including people with some types of epilepsy (including photo-sensitive epilepsy), 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 helps prevent triggering of seizures.

Barriers can include:

Multiple Disabilities (scenario -- "teenager")

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 transcript 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.

Aging-Related Conditions (scenario -- "retiree")

Changes in people's functional ability due to aging can include 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.

4. Assistive Technologies and Adaptive Strategies

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 sometimes referred to as adaptive software or hardware.

Some assistive technologies are used together with graphical desktop browsers, text browsers, voice browsers, multimedia players, or plug-ins. Some accessibility solutions are built into the operating system, for instance the ability to change the system font size, or configure the operating system so that multiple-keystroke commands can be entered with a sequence of single keystrokes.

Adaptive strategies are techniques that people with disabilities use to assist in using computers or other devices. For example someone who cannot see a Web page may tab through the links on a page as one strategy for helpinjg skim the content.

Following is a list of the assistive technologies and adaptive strategies described below. This is by no means a comprehensive list of all such technologies or strategies, but rather explanations of examples highlighted in the scenarios above.

Alternative keyboards or switches (scenario -- "reporter")

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 and refreshable braille (scenarios -- "accountant" and "teenager")

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. Refreshable or dynamic 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. Refreshable braille displays can be incorporated into portable braille devices with the capabilities of small computers, which can also be used as interfaces to devices such as information kiosks.

Scanning software

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.

Screen magnifiers (scenarios -- "teenager" and "retiree")

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.

Screen readers (scenarios -- "accountant" and "teenager")

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 recognition

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.

Speech synthesis (speech output) (scenario -- "accountant")

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.

Tabbing through structural elements (scenario -- "accountant")

Some accessibility solutions are adaptive strategies rather than specific assistive technologies such as software or hardware. For instance, for people who cannot use a mouse, one strategy for rapidly scanning through links, headers, list items, or other structural items on a Web page is to use the tab key to go through the items in sequence. People who are using screen readers -- whether because they are blind or dyslexic -- may tab through items on a page, as well as people using voice recognition.

Text browsers

Text browsers such as Lynx are an alternative to graphical user interface browsers. They can be used with screen readers for people who are blind. They are also used by many people who have low bandwidth connections and do not want to wait for images to download.

Visual notification

Visual notification is an alternative feature of some operating systems that allows deaf or hard of hearing users to receive a visual alert of a warning or error message that might otherwise be issued by sound.

Voice browsers

Voice browsers are systems which allow voice-driven navigation, some with both voice-input and voice-output, and some allowing telephone-based Web access.

5. Scenario References

This section includes a selection 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 1.0.

This section is not a comprehensive listing of accessibility provisions in the three sets of guidelines.

Alternative text (scenario -- "accountant")

Controlling color (scenario -- "online shopper")

Controlling presentation with style sheets (scenarios -- "online shopper" and "retiree")

User override of author style sheets (scenarios -- "online shopper" and "teenager")

Providing full keyboard support (scenario -- "reporter")

Using access keys for shortcuts (scenario -- "reporter")

Making multimedia accessible (scenarios -- "online student" and "teenager")

Using column and row headers in tables (scenarios -- "accountant" and "teenager")

Expanding abbreviations and acronyms (scenario -- "accountant")

Synchronizing screen display with audio and braille rendering of information (scenario -- "accountant")

Supplement text with graphic or auditory presentations (scenarios -- "online student," "teenager," "supermarket assistant")

Allow user to freeze moving context and scrolling text (scenarios -- "online student" and "retiree")

Avoid auto-refreshing pages (scenario -- "retiree")

Avoid causing "pop-up" windows (scenario -- "retiree")

Use clear and consistent navigation mechanisms (scenario -- "supermarket assistant")

Use clearest and simplest language appropriate (scenario -- "supermarket assistant")

Use a consistent style of presentation across pages (scenario -- "supermarket assistant")

Enable device independence (scenario -- "teenager")

Label frames (scenario -- "teenager")

Provide multiple search types (scenario -- "supermarket assistant")

6. General References

[ATAG10]
"Authoring Tool Accessibility Guidelines 1.0", J. Treviranus, C. McCathieNevile, I. Jacobs, and J. Richards, eds., 3 February 2000. W3C Recommendation: http://www.w3.org/TR/2000/REC-ATAG10-20000203/. 
[WCAG-CURRIC]
"Curriculum for Web Content Accessibility Guidelines,"...
[SMIL]
"Synchronized Multimedia Integration Language,"..
[UAAG10]
"User Agent Accessibility Guidelines", J. Gunderson and I. Jacobs, eds., 28 July 2000. W3C Recommendation: http://www.w3.org/TR/2002/REC-UAAG10-20021217/.
[WCAG10]
"Web Content Accessibility Guidelines 1.0", G. Vanderheiden, W. Chisholm, and I. Jacobs, eds., 5 May 1999. W3C Recommendation: http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/.
[WAI-Home]
"WAI Home Page", 1997-2000. http://www.w3.org/WAI/.
[WAI-Resources]
"WAI Resources", 2000-2001. http://www.w3.org/WAI/Resources/.

7. Further Reading

About disabilities

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, and is 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; information about assistive technologies used with the Web; and information from organizations that focus on accessibility strategies for using information technologies and telecommunications. One way to start is by doing Web searches on the terms used in this document.

About the Web Accessibility Initiative

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 Department of Education's National Institute on Disability and Rehabilitation Research; the European Commission's Information Society Technologies Programme; Government of Canada, Industry Canada; Fundacion ONCE, HP, IBM, Microsoft Corporation, SAP, Verizon Foundation, and Wells Fargo. Additional information on WAI is available at http://www.w3.org/WAI/.

About the World Wide Web Consortium (W3C)

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 Computer Science and Artificial Intelligence Laboratory (CSAIL) 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. For more information about W3C, see http://www.w3.org/.

8. Acknowledgements

We would like to thank the following people who have contributed substantially to this document:

Some initial material drawn from Gregg Vanderheiden and Kate Vanderheiden. Additional contributions from Kathleen Anderson, Andrew Arch, Harvey Bingham, Helle Bjarnø, Alan Cantor, Alan Chuter, Dave Clark, Libby Cohen, Cynthia Curry, Deborah Dimmick, Sylvie Duchateau, Julie Howell, Ian Jacobs, Marja-Riitta Koivunen, Chuck Letourneau, William Loughborough, Charles McCathieNevile, Sailesh Panchang, Doyle Saylor, Sheela Sethuraman, Henk Snetselaar, Jeff Turner, Carlos Velasco, Eric Velleman, and participants of the Education and Outreach Working Group.