Accessibility and Usability For Web Sites: An Introduction to Web Accessibility

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Accessibility and Usability For Web SitesAn
Introduction to Web Accessibility
http//www.ukoln.ac.uk/web-focus/events/workshops/
eemlac-2005-01/

• Brian Kelly
• UKOLN
• University of Bath
• Bath

Email B.Kelly_at_ukoln.ac.uk URL http//www.ukoln.ac.
uk/
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Background To The Web

• World Wide Web developed by Tim Berners-Lee to
• Provide universal access to digital resources
• Avoid problems of
• Device dependencies data islands on PCs, Apple
  Macintoshes, Unix systems,
• Application dependencies data islands between MS
  Word, WordPerfect, Wordstar, users)
• Vendor dependencies monopoly stifling
  competition and raising prices patent holders
  seeking licence fees (cf. GIF)
• User dependencies data islands due to
  disabilities e.g. visual impairments, hearing
  impairments, lack of motor skills,

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Background To Web Accessibility

• "The power of the Web is in its universality.
  Access by everyone regardless of disability is an
  essential aspect."
• Tom Berners-Lee, lthttp//www.w3.org/WAI/gt
• W3C (the consortium responsible for Web
  standards) set up WAI (Web Accessibility
  Initiative) to enhance accessibility of the Web.
  Key deliverables include
• Web Content Accessibility Guidelines (WCAG)
  guidelines on creating accessible resources
• Authoring Tool Accessibility Guidelines (ATAG)
  guidelines on writing authoring tools which will
  help to create accessible resources
• User Agent Accessibility Guidelines (UAAG)
  guidelines on writing browsers which provide
  accessibility support

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Quick Tips For Web Accessibility
See lthttp//www.w3.org/WAI/References/QuickTips/gt

• Images animations Use the alt attribute to
  describe the function of each visual.
• Image maps Use the client-side map and text for
  hotspots.
• Multimedia Provide captioning and transcripts of
  audio, and descriptions of video.
• Hypertext links Use text that makes sense when
  read out of context. For example, avoid "click
  here."
• Page organization Use headings, lists, and
  consistent structure. Use CSS for layout and
  style where possible.
• Graphs charts Summarize or use the longdesc
  attribute.
• Scripts, applets, plug-ins Provide alternative
  content in case active features are inaccessible
  or unsupported.
• Frames Use the noframes element and meaningful
  titles.
• Tables Make line-by-line reading sensible.
  Summarize.
• Check your work Validate. Use tools, checklist,
  and guidelines at http//www.w3.org/TR/WCAG

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Accessible Web Sites

• Accessible Web sites should
• Use compliant HTML if a page is valid it is more
  likely to be displayed sensibly on a range of
  devices
• Use CSS to define the appearance of HTML tags
  this has several benefits
• Users can use their own style sheet or switch off
  the style sheet (e.g. colour scheme or text sizes
  cause difficulties in reading)
• Web site owner can define appearance in small
  number (1) of CSS files and can easily change
  this file
• Pages can change appearance on devices such as
  PDAs, digital TVs, etc
• Provide textual descriptions of multimedia (e.g.
  ALT tags for images)
• Comply with the letter and spirit of W3C
  standards avoid proprietary extensions (e.g.
  BLINK, FRAME, etc.) avoid file formats (e.g.
  PDF, Flash, ),

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Doesn't Everyone Use IE?

• How do people with disabilities access the Web?
• Zooming In Many people with disabilities have
  some sight and may need to zoom in in areas of a
  Web browser. It is therefore essential that Web
  sites dont use fixed fonts, for example (even if
  this allows users to change a corporate
  look-and-feel).
• Speaking Browsers Blind users may use a speaking
  browser which speaks words on the page. Note
  that speaking devices can't understand text
  contained in images so avoid this (or give
  appropriate ALT text for images).
• Special pointing selection tools Users with
  physical disabilities may not be able to use a
  mouse. Therefore Web sites should be usable
  without a mouse. For example, a Web form should
  be designed so that tabbing moves the cursor in a
  sensible order.
• PDAs, Mobile Devices, Digital TVs, Users with
  physical disabilities may prefer use of PDAs or
  other mobile devices. And digital TV access may
  help a widening participation agenda

And everybody doesn't use IE increasing numbers
are moving to Firefox (which featured in a leader
column in the Guardian in Nov 2004)
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Checking Compliance

• You need to be able to check that your Web site
  is accessible
• For auditing existing Web sites
• To identify problems in your workflow processes
• For acceptance testing
• Techniques for checking compliance include
• Use of automated tools such as Bobby, WAVE,
• Manual testing

NOTE Automated tools are not able to verify that
Web sites are accessibility only that they are
not accessible. For example Bobby can report if
images do not have ALT tags, but not that the ALT
tag is meaningful.
ltimg src"logo" alt"UKOLN logo"gt gt
ltimg src"logo" alt"" gt
ltimg src"logo" alt"a picture"gt
ltimg src"logo" alt"Bath Abbey"gt
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Any Questions?

• Any Questions?