The DDA (Disability Discrimination Act) states that service providers must not discriminate against disabled people. A website is regarded as a service and therefore falls under this law, and as such must be made accessible to everyone.

Some organisations are making accessibility improvements to their websites, but many are seemingly not making the accessibility adjustments. Disabled people don't access their website, they say, so why should they care?

Why you should care about disabled Internet users

The statistics on the number of users who may face difficulties due to your website's accessibility are quite startling:

* There are 8.6 million registered disabled people in the UK - 14% of the population (source: DRC)

* One in 12 men and one in 200 women have some form of colour blindness - 9% of the UK population (source: Institution of Electrical Engineers)

* Two million UK residents have a sight problem - 4% of the population (source: RNIB)

* There are 12 million people aged 60 or over - 21% of the UK population (source: UK government)

Although there is inevitably some overlap between the aforementioned groups, adding up these numbers provides a total of 48% of the UK population that could potentially face problems with your website's accessibility. That's an extraordinarily high number.

It's not just disabled users who can't access your website

Non-disabled people may also experience difficulties with your website's accessibility. Not everyone is viewing your website on the latest version of Internet Explorer, with all the plug-ins and programs that you may require them to have for optimal access.

If your website relies on images, Flash or JavaScript, and fails to provide alternatives, then your website won't be accessible to a number of web users. The following examples are a common occurrence:

* Users on slow connections regularly turn images off to enable a quicker download time. Some browsers, such as the text-only Lynx browser do not display images at all.

* Not every user has downloaded the latest Flash program that's needed to access your site. Additionally, the download time on Flash websites often takes so long that users lose patience and don't even wait to see the content. Just 25% of web users in the UK are connected to the Internet via broadband (source: National Statistics).

* JavaScript is a scripting language that can cause changes to a page, often through mouse functions, buttons, or other actions from the user. For example, pop-ups are opened using JavaScript. JavaScript is unsupported by about 5% of web users, either because they have turned it off to prevent pop-up adverts or because their browser doesn't support it (source: The Counter). Any JavaScript-driven content provided on your website won't be accessible to these users.

* PDAs, mobile phones and WebTV have limited support for large images, Flash and JavaScript. You can test your website by downloading the free WebTV viewer. You can also check how your website looks on a mobile phone with the Wapalizer. Don't underestimate the importance of this: in 2008 alone an estimated 58 million PDAs will be sold (source: eTForecast) and one third of the world's population will own a wireless device (source: ClickZ)