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Home > Articles > Webmaster resources > Accessibility vs Usability

Internet Magazine, January 2004

Access? That'll do nicely.

Your site might comply with accessibility guidelines, but is it easy for people with disabilities to use? In the eyes of the law, usability is everything. By Sean McManus

Accessibility versus usability

Accessibility and usability are often lumped together, but they're not the same. "Accessibility is ensuring that all users can access all services and content," says Léonie Watson, acting chair for the British Web Design and Marketing Association's first workgroup for accessibility and usability. "Usability is ensuring that the process of accessing services and content is as intuitive and efficient as possible."

Watson is blind and uses the Jaws (v5.0) screenreader with Outlook Express and Internet Explorer. "Through the net I'm able to communicate with friends and colleagues," she says. "I can do my banking and bill paying with relative ease and I can read the newspaper, locate articles and research far more readily than might otherwise be possible. The sites for doing these things are still some way from ideal accessibility and usability, but despite this they transfer control back to the user. You can't argue with the ability to Christmas shop online: no need for someone to describe each product to you, no need to worry that you've missed something."

One myth about accessibility is that you're catering for an insignificant minority. According to the RNIB, Tesco.com secured £13 million a year in new business by building its accessible site and usability expert Jakob Nielsen points out that accessibility issues will affect us all one day. "It's a continuum," he says. "You have people with very severe impairments to people with very minor impairments and when you get up into your 40s you start getting into that category of minor impairments. I'm already in a situation where websites with fixed font sizes are getting harder to read for me."

Even if you've vetted your site with the comprehensive WAI accessibility checklists, it's no guarantee your site will be useful to those using assistive devices. Nielsen says: "There is a great difference between technical accessibility and the ability for people with disabilities to use a website easily. Just consider the problems that users without any disabilities have using many regular websites. These sites are 'accessible' for these users in the sense that they can see everything. That doesn't mean that the design makes sense or that people can find their way around."

Making your site accessible

The first step towards usable, accessible designs is to ensure compliance with accessibility guidelines. A-Prompt (link removed, software no longer available) is a freeware Windows package that makes it easier. It'll examine your pages and help you to identify potential problems and missing mark-up. Where possible, it'll ask you for supplementary information (such as missing descriptive text for pictures) so it can insert it in the right place in your webpage.

Refer to the software's context-sensitive help to make sure you provide useful information.

"One of the most common things I encounter is a site where the designer has included alt text for all images, but hasn't really understood the impact of what they are doing," says Watson. "Spacer images that have been given an alt="spacer" attribute are one example. You may find as many as 20 or 30 spacer images on a page and if each one is announced as "spacer" it quickly becomes annoying. In this particular instance, a null alt text (alt="") would render the spacer images as invisible to a blind person as they are to a sighted one. Using null alt attributes steps beyond the guidelines to true user centred design."

Accessibility is about using HTML to add redundancy and give the user a choice about how to experience your content. It's not stripping out anything visually appealing and publishing text-only websites, an oft-repeated myth and one of Watson's pet peeves. "Once upon a time text-only sites were a logical solution to a problem. Now they are just a sorry excuse for accessibility," she says. "Being able to share a common experience, whether on the net or elsewhere, is vitally important for true equality."

To see how accessible your site is, try to break it by tampering with your browser settings. If you can still use it with huge text and without any images, plug-ins or a mouse, you're well on the way.

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