The Disability Discrimination Act says that websites must be made accessible to disabled people. So how can you check that your website is up to par? There are a number of basic tests you can make to address some of the main issues that provide a good start in increasing accessibility to your site visitors:

1. Check informational images for alternative text

Place the cursor over an informational image, for example, the organisation logo. Does a yellow box appear with a brief, accurate description of the image? For users whose browsers do not support images, this alternative text is what they will see (or hear) in place of the image.

2. Check decorative images for alternative text

Place the cursor over a decorative image that does not have any function other than to look nice. Does a yellow box appear with a description of the image? It should not. There is no reason for users whose browsers do not support images to know that this image is there, as it serves no purpose.

Be careful though as this is not a foolproof test. If a yellow box does not appear, this could mean one of two things:

- The alternative text of the image is assigned a null value, which means that it will be ignored by browsers that do not support images. This is the ideal scenario.

- The alternative text of the image is simply not set at all, which means that users whose browsers do not support images will be alerted to its existence but will be unable to find out what purpose it carries ? something which is very frustrating! This is certainly not the desired outcome.

3. 'Listen' to any video or audio content with the volume turned off

If you turn your speakers off, you are clearly unable to listen to, or follow, any audio content. This situation is faced by a deaf person on a daily basis. Ensure your website supplies written transcripts, so that deaf people can understand the message that your website is conveying.

4. Check that forms are accessible

Usually there is prompt text next to each item in a form. For example, a contact form might have the prompt text 'name', 'e-mail', and 'comments', each one next to a box where your site users will enter the information. When you click on the prompt text, does a flashing cursor appear in the box next to that text? If not, your forms are inaccessible.

5. Check that text can be resized

In Internet Explorer (used by over 90% of Internet users) go to View > Font size > Largest. Does the text on your website increase in size? If not, then your website is inaccessible to web users with poor visibility.

6. Check your website in the Lynx browser

The Lynx browser is a text-only browser and does not support many of the features that other browsers such as Internet Explorer have. You can check how your site looks in this browser with the Lynx Viewer, available at http://www.delorie.com/web/lynxview.html. If your website makes sense and can be navigated through the Lynx browser, then it will be fulfilling many of the web accessibility guidelines.

7. Check that you can access all areas of your website without the use of a mouse

Can you navigate through your website using just tab, shift-tab and return? If not, then neither can keyboard- and voice-only users.

8. Check that there is a site map

Can you find a site map? If not, then neither can people who are lost on your website.

9. Ensure link text makes sense out of context

Blind Internet users often browse websites by tabbing from one link to the next. Does all the link text on your website make sense out of context? 'Click here' and 'more' are two common examples of non-descriptive link text.

10. Check your web pages with an automated program

Two programs available for free on the Internet are Bobby ( http://bobby.watchfire.com ) and Wave ( http://www.wave.webaim.org ). They are unable to provide you with all the information that you need, as some checks must be done by humans, but they can tell you some of the areas where your site might be going wrong.

This article was written by Trenton Moss. He's crazy about web usability and accessibility - so crazy that he went and started his own web usability and accessibility consultancy ( Webcredible - http://www.webcredible.co.uk ) to help make the Internet a better place for everyone.