How disabled users access the Internet

A helpful overview, thanks. I just had a few additional comments:

Internet users who have no sight at all may utilize a screen reader, which reads the content of the web page, or rather the HTML code of the page, back to them. These machines sift through the HTML code and the technology deciphers what needs to be read aloud and what should be ignored. You can download the IBM Homepage Reader for a free 30-day trial. Once you’ve downloaded it, go to your website, turn your monitor off, and try to navigate your website.

There are several other screen readers, including Jaws (the market leader) and Windows-Eyes. Unfortunately all these programmes are expensive and have only severely-limited demo versions, making testing quite difficult for well-meaning designers!

A cheaper way to gain an understanding of what users of screen readers hear is to use a text browser like Lynx, or use Opera in text browser emulation mode. This "linearises" the content of the page as a screen reader would. (Opera has many features useful for testing accessibility, detailed on this RNIB page.) You can also get a quick text-browser view of any website using Lynxview.

To take full advantage of the Internet, users with partial or poor sight may need to be able to enlarge the text on web pages. Check if your website allows them to achieve this on Internet Explorer by going to ‘View > Text size > Largest’.If your site is accessible to this group of users then the size of the text throughout the page will increase. Text embedded within graphics isn’t resizable and may cause difficulties for this group of web users.Users with poor vision may also use a screen magnifier to enlarge the text size. Again, text embedded within graphics may cause difficulties as it can appear blurry and pixelated when magnified.

As far as I’m aware the pixellation of magnified graphical text is not a significant impairment to its legibility. If you have heard otherwise, let me know.

I should also point out that many browsers are much less limited than Internet Explorer when it comes to magnifying content. Opera zooms both images and text. Gecko-based browsers (Firefox, Netscape 6+, Mozilla) can resize text regardless of how the page was coded. Users who are aware they have difficulty reading typical web pages are likely to use screen magnification software or one of these browsers.

That said, there is a large grey area of users with only slightly imperfect vision who might often want to increase text size. (I do so myself, when reading a lot of text on screen and want to lean back.) They would not consider themselves disabled, and most are unlikely to switch from the default browser, Internet Explorer. For that reason, making sure fonts are resizable in IE is still very important.

Finally, I would also advise anyone interested in testing the accessibility of websites to have a look at the Accessify favelets (also known as bookmarklets) which are browser add-ons that help in testing accessibility.

Screen readers and screen magnification can also be viewed in action in these videos produced by the University of Wisconsin.