A List Apart


What Is Web Accessibility?

A few weeks ago A List Apart published my article about web accessibility and the UK legal requirements surrounding it. The article provoked a heated discussion and what seemed like a lot of confusion surrounding web accessibility, which is what led me to write this follow-up article.

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What follows will be familiar to many ALA readers but new to a few. As with all overviews, it is somewhat oversimplified and does not cover exceptions and edge cases. The editors and I hope that it will provide a useful touchstone for those readers who have been standing at the shores of accessible web design, fearing sharks where there are only gentle waves.

About this article

This article will not tell you how to make an accessible website. That’s already been done by Mark Pilgrim in his excellent Dive into Accessibility and by Joe Clark in his extensively researched and beautifully written Building Accessible Websites.

Although they can be vague and confusing in places, after reading Pilgrim and Clark you might also want to check out the W3C accessibility checkpoints. I’m not going to preach at you about the benefits of accessibility — I’ve already done that elsewhere. Instead, this article will tell you who you need to consider when making your website and what their unique requirements are. So, let’s get started …

Disabled users

Blind users

Web users who have no sight at all may utilize a screen reader, which reads the content of the web page, or rather the HTML, back to them. This software, which sits between the user and the browser, sifts through the HTML markup and the technology deciphers what needs to be read aloud and what should be ignored.

Windows users, try it yourself with the IBM Homepage Reader, which you can download for a free 30-day trial. (You’ll need a recent version of Microsoft Windows and a fairly capable PC with Pentium processor or equivalent.) Once you’ve downloaded it, go to your website, turn your monitor off, and try to navigate.

Open source screen readers for Linux include Emacspeak and IBM ViaVoice.

The next major revision to Mac OS X will include built-in spoken interface technology. Mac OS X users who complete a brief questionnaire may be able to download and use a preview version.

Partial/poor sight

To take full advantage of the Internet, users with partial or poor sight need to be able to enlarge the text on web pages.

As this magazine’s readers know, Opera, IE5 Macintosh Edition, Mozilla/Netscape/Firefox, Konqueror, Safari, and all other modern browsers but one provide text resizing widgets that work no matter what method a designer has been used to specify type size.

But for IE/Windows users to be able to resize text, you must specify the font size in terms of %, em or a relative value (small, medium, etc.) as this magazine does, or use a basic or advanced style sheet switcher to provide this functionality.

Users with poor vision may also use a screen magnifier. You can download a screen magnifier for free and try it for yourself.

Color blindness

It is estimated that one in 12 men and one in 200 women have some form of color blindness. You can check how Internet users with different strains of color blindness are viewing your website with Vischeck.

Deaf users

Deaf users are able to access the Internet in much the same way as non-deaf people with one key exception — audio content. If it’s a key function of your website for people to be able to hear a message, then be sure to provide written transcripts at the very least. (To do more than the very least, see Chapter 13 of Joe Clark’s Building Accessible Websites.)

Keyboard/voice only users

Some of your site users don’t have access to a mouse when browsing the Internet. Try putting yourself in their position by navigating your website using only tab, shift-tab, and the return keys.

Other users

Other people who may access your website that have disadvantages include:

  1. Epileptic users who must always be careful to avoid seeing flickering between 2 and 55 Hz
  2. Web users from outside your industry who may not understand industry jargon or acronyms
  3. Web users whose first language is not English and who may not be able to comprehend complicated language

To really put yourself in the position of one of these web users try out the DRC’s inaccessible website demonstration.

New (and old) technology

PDAs and mobile devices

The number of people accessing the Internet from handheld devices is increasing at a massive rate — almost three million PDAs were sold in 2002 in Western Europe and in 2008 alone there’ll be an estimated 58 million PDAs sold.

Handheld devices generally have ropey support for large images, JavaScript, Flash and (too often) even CSS. Their width can be as small as 120px with horizontal scrolling not an option. Read Webmonkey’s last-ever article which was about small screen web development. You can also check your website’s accessibility on a handheld device for free with the Wapalizer.


WebTV has a maximum width of 575px and horizontal scrolling isn’t possible. You can download the free WebTV viewer and see how your website looks on a TV screen.


Approximately 6% of web users are surfing the web with no support for JavaScript. This could be because they’re using a browser that doesn’t support JavaScript (such as the text-only Lynx browser) or they’ve turned JavaScript off for security or to avoid popups.

Slow connections

Broadband isn’t nearly as widespread as you’d expect. In the UK, for example, just one in six Internet households were hooked up to broadband this time last year. Users on slow connections might turn images off to enable a quicker download time. Some browsers, such as the Lynx browser do not display images at all. Make sure you put in those ALT attributes!

And finally …

Any web developer with basic HTML and CSS design knowledge, and a bit of time on their hands, can easily learn and implement web accessibility — it’s not brain science after all. Web accessibility is all about following design standards and then adding in a few simple accessibility features. It’s not just about disabled users being able to access your website — it’s about everyone being able to access your website.

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