On this site
- User agent
- Any software program or device that is used to display content on the Web. There are
W3C standards for user agents just as there are for Web content. In an ideal world,
both content and user agents would be fully compliant with the standards; however,
Web technology evolves so rapidly that this is seldom realized in practice.
- Assistive technology
- Any software program or device that is used to assist persons with
disabilities. Many of these focus on computers and the Web, but many perform other functions.
A magnifying glass, for example, is a simple assistive technology for people with
- Screen reader
- A software program or device that reads the information on a computer screen aloud.
Screen readers handle operating system commands and other software applications
as well as Web pages. They are commonly used by the blind, but are expensive and
require a fairly long period to learn adequately. Popular screen readers include
Jaws from Freedom Scientific, Window Eyes from GW Micro, and Hal from Dolphin. All
run on the Windows platform. Apple's VoiceOver utility comes as part of the Mac
- Talking browser
- Similar to a screen reader, but only works on Web content.
Other assistive technologies
- Most operating systems have built-in adaptations for mild visual
disabilities. There is also third-party screen-magnification software that may
provide better readability than the operating system can do.
- Those who read Braille can use a special device that functions much like a screen
reader except that it uses a set of moving pins to display the letters.
- Those with limited or no use of their hands can use a variety of devices including
mouth straws and voice-recognition software.
Accessibility jargon decoded
Accessibility specialists tend to sprinkle their conversations with
acronyms, abbreviations, and other unique terms just as readily as do computer scientists,
plant growers, jazz musicians, or members of any other "in" group. Here are the ones that are most
important for a general understanding of the topic. Learn more with our
- Section 508
- Part of the United States Rehabilitation Act of 1973, as amended in 1998 to
include information technology (29 U.S.C. 794d). Specifically, Part B of
Section 508 contains guidelines for software [para. 1194.21(a)–(l)] and for
the Web [para. 1194.22(a)–(p)]. For the full text of this section, see
This is the current standard for Federal agencies; it has also been adopted by
a number of States. It is somewhat outdated, however, and is now being revised.
- Section 504
- Part of the same U.S. law as Section 508, Section 504 is much broader and less
technical in scope. It applies not only to Federal agencies, but to other organizations
(such as universities) that receive Federal funding. Simply stated, it requires that
these organizations provide equally effective access to information
resources for persons with disabilities. Equally effective access may include
such factors as timeliness of delivery as well as simple ability to use a resource
in a mode (visual, auditory, tactile) that can be used by the disabled person.
- Not a standard but an agency with important legal powers: the Office for
Civil Rights of the U.S. Department of Education. If a university student, for example,
files a complaint that he or she has been denied equally effective access to resources,
it's the OCR that investigates the complaint and, if warranted, initiates legal
action against the offending organization. For more information, see the
OCR home page
- World Wide Web Consortium, the group that develops standards for the Web.
These standards are actually "recommendations," and although they are agreed
to by a broad representation from industry and education, they are not binding.
For further information, see w3.org.
- Web Accessibility Initiative, a group within the W3C that develops and advocates
standards for accessible Web content, authoring tools, and user agents (the
software such as browsers that display Web content for us). For further information,
see the W3C WAI home page.
- WCAG 1.0
- Web Content Accessibility Guidelines, verson 1. Developed by the W3C/WAI, this was
the first set of technical guidelines aimed at making Web pages accessible for
readers with a wide variety of disabilities. This version was based on technology
of the late 1990s, and is now somewhat out of date. The W3C site contains the
full set of guidelines.
- WCAG 2.0
- Web Content Accessibility Guidelines, verson 2. Follow-on to WCAG 1, this
version has now been released in its final form. Much broader in scope than version 1, it is
written to be technology-neutral in its principles and success criteria. It also
includes sufficient techniques for using Web technology accessibly. WCAG 2 can
and should be used immediately by developers, since it can facilitate compliance
with any other legal or technical standards that they may be required to meet.
The W3C site includes a useful quick
reference to WCAG 2.
- HTML (or XHTML)
- HyperText Markup Language (or eXtensible HyperText Markup Language); the basic
programming language for all Web content. The W3C site contains the
HTML standard, the
XHTML standard, and the latest
Regardless of which version is used for a Web site,
the code should be written to comply exactly with that standard; this makes it
easy for browsers and other user agents to display it as intended.
Modern HTML/XHTML code is used only to mark up the structure of a
document; how the content is displayed is controlled by style sheets.
- Cascading Style Sheets, often just called style sheets. In modern design, all presentation
on the Web—screen, print, and even spoken—is coded in style sheets.
Like HTML, CSS code should be written to comply with the
- The Accessible Rich Internet Applications Suite, according to the W3C,
"helps with dynamic content and advanced user interface controls developed
new standard, but promises to make dynamic pages much more accessible
than they have been so far. For more information, see the
WAI-ARIA home page
- MathML provides a way
to display mathematical expressions on the Web. This makes it possible for disabled
persons to access technical information that they could not have read in a book.
It is not yet in wide use, but becoming more available.
Yet another W3C project. Similar standards
are being developed for chemistry, music, and other specialized notations.
- An international standard for digital talking books, developed by a consortium that is
not part of the W3C. Daisy books give visually disabled persons access to the book's
content that closely resembles what readers of printed books can do. For more
information, see the Daisy consortium page.
The legal stuff
Copyright 2008, by Tom Jewett, tom [at] tomjewett [dot] com.
Please see our home page for full legal notices.