A Complete Guide to Web Design

24 Chapter 2 – Designing for a Variety of Displays

Accessibility

Web Design in a Nutshell, eMatter Edition

Sight-impaired users may simply use a device that magnifies the screen for easier

reading, in which case there are no special design requirements. Many vision-

impaired users use a text browser (such as Lynx) in conjunction with software that

reads the contents of the screen aloud. Some use devices that translate the text

into Braille. Either way, there is a greater reliance on the structure and the text

within the document. Content in graphics may be completely lost.

Designing Accessible Pages

The following list presents a few simple measures you can take to make your

pages more accessible.

• Provide alternative text for all images (via thetag’saltattribute).
  Make the alternative text rich and meaningful. Addingalttext should be
  standard procedure for all web page creation; in fact, in the new HTML 4.0
  specification, thealtattribute is now arequiredpart of thetag. (See
  Chapter 9,Adding Images and Other Page Elements, for more information.)


• Add periods at the end ofalttext so a speech device can locate the logical
  end of the phrase.


• When linking a graphic, provide a caption under it that also serves as a text
  link.


• Always provide text link alternatives for imagemaps.


• Offer a text-only version of the whole site from the home page.


• Provide transcripts or descriptions of audio clips to make that content accessi-
  ble to those with hearing impairments.


• Use caution in relying on PDF (Adobe’s Portable Document Format) to deliver
  information. If you are using PDF files, provide an HTML alternative. You may
  also provide a link to Adobe’s site where users can download software tools
  that convert PDF files to text format for delivery by nonvisual browsers (http://
  access.adobe.com).


• Provide alternative mechanisms for online forms, such as a text-based order
  form or a phone number for personal assistance.


• Avoid thetag, which is said to wreak havoc with Braille and speech
  displays.


• Be sure content in tables makes sense when read sequentially in the HTML
  source.


• Be aware that misuse of HTML structural tags for presentation purposes (such
  as using the

  tag purely to achieve indents) hinders clear com-
  munication via a speech or Braille device.
  For a thorough list of guidelines for accessible HTML authoring, visit the W3C’s
  recommendations and checklist athttp://www.w3.org/TR/WD-WAI-PAGEAUTH.
  If you would like to check how accessible your web page is, try running it
  through a validator, such as Bobby (http://www.cast.org/bobby /), that will scan
  your page and point out accessibility issues.