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Developing for Accessibility

Accessibility, as the name suggests is about making websites accessible to as many users as possible. Unfortunately, not everyone on the planet has 20/20 vision, or full use of their hands, which can make using traditional web sites difficult – why should they be disadvantaged by not being able to harness the plethora of information out in cyberspace? Even beyond that, there are many able-body web users that are using non-standard browsers and software to access websites. PDAs, mobile phones and hand held game machines (such as the Sony PSP) are examples of systems that have restricted screen sizes and memory footprints which makes packing a full blown web browser impossible. Another benefit of an accessible website is it makes the search engine robots’ job much easier.

Different ways of using the web

The web is no longer confined to the walls on universities, or geeky tech type people – 14 million people in Australia have access to the internet [Nielsen/NetRatings]. Even if you ignored 5% of that audience, that is potentially 700,000 people that cannot access your website. This is especially relevent to government websites who theoretically should be targeting everyone.

There is no way of guaranteeing that all of these users are using standard desktop setups either: some variations include:

  • Screen readers: These programs are used by sight-impaired users. They read in the HTML markup and read it out using a synthesised voice. These system tend not to understand JavaScript or Flash.
  • Braille readers: Again used by sight-imparied users. Very much like a screen reader, except they output the page in Braille
  • PDA/Mobile phone: very handy for those who are out on the road a lot. These usually have a reduced screen size, and limited memory. They also have different method of inputting data, so things like JavaScript menus will probably not work.
  • Slow internet connections: People out in the bush (Or even the suburbs) may not be able to get broadband, or reliable modem connections. So there may still be a number of people that try to reduce bandwith by switching off images.
  • Text-only browsers: Not really sure why you would still use these other than because you can – although, they can provide a good indication of what your site looks like to a search engine spider.

Accessibility and Standards

The basics of accessibility can be acheived by following the World Wide Web Consortium (W3C) standards documents. These standards are about creating semantic, structured layout that can easily be intepreted by any system that understands the standards. The standards break up the structure layer and the presentation layer, by usingl Cascading Style Sheets (CSS), which effectively gives the designer control over how an element looks without destroying the document structure. The names of HTML tags have been carefully selected to decribe document elements. Unfortunately, in the old days, many designers abused the default display properties of some elements, misusing them to present information in a certain style.

For example, an old trick to indent text would be to wrap it in tags. It is hard to image how a screen reader would handle this – it comes across some text it expects to be an un-ordered list, only to find a block of text. The correct way of doing this would be to wrap it intags, and use the CSS property padding-left to indent the whole block.

Before CSS, it was common to mix up the order of items in the HTML to fit the presentation of the page. This means that a user running a screen reader would have the contents read out in the wrong order… Not very usable at all.

Don’t rely on colour

Colour blindness is a condition that stops the sufferer for perceiving certain colours. This can create two potential problems for the web designer – foreground-background contrast and colour for notification. Any user with normal vision knows how hard it is to read dark blue text on a black background – because the contract between the two colours in not enough. However, there are certain colour combinations that would be fine for non-colour blind people, but would work for those that did have the deficiency.

To be continued… [I’ve to go to my exam now – this will be interesting]

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