Web accessibility is an attempt to make content available in equal measures to every user of the internet, regardless of any physical or mental disability.

Accessibility is not just our moral obligation as reasonable human beings, but also a legal obligation too. Fortunately designing with accessibility in mind from the beginning, means that implementation is nothing more complicated than the addition of a few extra lines of code.

Restricting accessibility

A web application can be thought of as having three very distinct layers:

• The Content Layer (xhtml) – The raw material of every website; text, images and links.
• The Style Layer (css) – The visual design of the content on the screen; positioning, font size, colours etc.
• The Behaviour Layer (JavaScript, VBScript) – This deals with how the user interacts with the page.

Accessibility is always compromised when the Content Layer becomes dependant on either the Style or Behaviour layer. For example if a site were to rely on a JavaScript Event Handler to display a menu the site would be said to have device dependency and therefore poor accessibility.

Even the likes of Google can make this mistake. In their latest redesign they neglected to make a non JavaScript version of the menu on their home page, cutting off functionality (and potential revenue) from thousand of users. (Gilbertson, 2007)

As the web itself becomes the dominate computing platform – as opposed to an operating system like Windows relying on every user sitting behind a desktop PC using Internet Explorer is a strategy that will ultimately prove unsustainable.

A modular design approach to the Content, Style and Behaviour layers will allow more users to interact with the a site in the richest way possible, regardless of the User Agent they use; from iPhone to screen reader to the highest spec PC.

Improving accessibility

Improving accessibility involves optimising the visibility of content for any given User Agent. This can be achieved by following best practices with coding such as the W3C specifications.

Practically this means using the <noscript> tag whenever we have JavaScript functionality. Inside this tag we provide an alternative means of achieving the behaviour.

With images we always provide ‘alt’ (alternative) text.

Redundant tags attached to the JavaScript functionality should also be removed.

As well as being tested for good accesibility with sites such as www.cynthiasays.com the code should undergo real world testing with a range User Agents such as screen readers like JAWS and Window-Eyes .

Ultimately a site should aim to build a device matrix taken from information supplied in the HTTP Accept header. Based on this a number of XHTML templates would be used to deliver the site in a range of formats to optimize the experience for everyone.