There is plenty of guidance available, from legislation such as the Disability Discrimination Act and the Disability Equality Duty, specific recommendations in the form of the Web Content Accessibility Guidelines (WCAG) 2.0 and even an enforcing body, the Equality and Human Rights Commission.
But the majority of websites are still not accessible to those dependent on using keystrokes instead of a mouse, nor those using screen-reading technology or voice recognition software. In addition, many of these tools do not work on a mobile platform, so anyone using a handheld device may be similarly prevented from achieving full access. The majority of providers still flout the guidelines, ignoring even the most basic requirements such as adding "alt text" for pictures and ensuring that functionality of content is operable through a keyboard interface.
Two main approaches have been adopted to try to change the situation.
The first is to raise awareness by improving the understanding and skill set of web teams. Standards such as WCAG 2.0 and organisations such as OneVoice for Accessible ICT Coalition are making tremendous strides in this area.
But a growing impatience with the current circumstances has been the motivating force behind the second approach to change the situation - a series of third-party solutions devised to improve the situation for those who are struggling to navigate their way around cyberspace.
One such system is Texthelp Systems' BrowseAloud product, which reads (accessible) web content aloud, thereby assisting people who find it difficult to read text online, including those with literacy difficulties, dyslexia and mild visual impairments, as well as non-native speakers.
Another successful add-on for readers with special educational needs is a symbol-based system such as that produced by Widgit. Widgit's augmentative software enables website owners to assist visitors to their site by producing symbols of suggested meanings when their mouse hovers over a word.
Some such enhancements - plug-ins or add-ons - require buy-in from the website provider, while others are installed on the user's machine and enhance the functionality of the browser. They often represent an accessibility bonus to a site, but their use should come with a note of caution.
Robin Christopherson, head of accessibility services at charity AbilityNet and himself blind, says: "These third-party solutions fall into two categories - those that enhance accessibility, and those that patch inaccessibility. Great tools such as Widgit's plug-in can help extend the level of access way beyond what even the most accessible sites can provide, in this case enabling those with very significant literacy difficulties to read a site by recognising symbols instead of words.
"Other browser plug-ins, or site add-ons, help get over some of the main accessibility shortcomings exhibited by a website. These tools are just as useful to the disabled surfer, but this 'patching' of inaccessibility should not be seen as a 'get-out clause' for site developers. They fulfil immediate and short-term requirements, but in the long-term are they not merely patching the inadequacies of inaccessible sites, which, after all, are unlawful, and therefore at risk of litigation?" he says.
"Responsibility falls quite clearly at the door of the site owner to raise the bar and let disabled people in."
Community-driven web aids
Christopherson highlights the emergence of empowering, community-driven innovations such as WebVisum to illustrate the point. Webvisum fulfils a vital need to enhance accessibility, while potentially easing pressure on site owners to raise their game. Arising out of genuine need, WebVisum is a browser add-on, available for Firefox, that provides tools and services that overcome some aspects of inaccessibility for blind and vision-impaired users - minimising their dependency on help from others.
With WebVisum - a tool requiring membership by invitation only - the user community drives image tagging and page enhancements. It offers dozens of features which make life easier for blind and vision-impaired web surfers, such as high-contrast page viewing, link and focus highlighting, and, perhaps most importantly, it provides automated and instant Captcha image solving.
Captcha codes are the most widely used verification scheme on websites to ensure that web content is accessed by humans only, but they are the bugbear of accessibility campaigners. Captcha has gained much popularity for its apparent effectiveness and ease of implementation, despite the obvious drawbacks the codes present to the vision-impaired.
And however efficient Captcha may seem to be, it has not prevented the creation of so-called "Captcha farms" in the Far East and Asia where workers are paid subsistence wages for "solving" thousands of codes a day to feed the insatiable spam industry.
WebVisum allows the blind user to press a keystroke that submits the Captcha image to a service that, within seconds, returns the code and automatically copies it to the clipboard.
But even WebVisum cannot handle all Captcha images. The introduction of a series of random logic-based questions, such as the service provided by textcaptcha.com, is a far more accessible alternative to the graphical option, but this has yet to be embraced widely. While the perception persists that tools such as WebVisum can handle all Captchas, perhaps this is not likely to change.
"Being blind I definitely appreciate the usefulness of a tool that can solve Captchas and add missing text labels to images. WebVisum even makes those tags available to every member of the WebVisum community so images come up already labelled," says Christopherson.
"Everything that can reduce the frustration of a broadly inaccessible web is in principle a good thing. However, a successful community effort risks a consequent reduction in the level of negative feedback to offending websites. Such a decrease in pressure is sure to make them feel less inclined to sharpen up their act."
Making visual adjustments
IBM's free Web Accessibility Toolbar is another user plug-in for Internet Explorer which can over-ride hard coding and make live visual adjustments to the site content to enhance usability. The toolbar offers a wide variety of accessibility features, including easy font size and colour contrast adjustments, magnification of a small portion of the screen, as well as the option of having the text read aloud with adjustable speech speed and volume controls. Once again though, a website's inherent flaws can cause major problems.
"Reformatting using these tools often results in overlapping, cropped or disappearing text. If the site has not considered what will happen when text is resized by the user, then a tool added on to make this possible will often have undesirable effects," says Christopherson.
Although he welcomes the introduction of such add-ons, Christopherson says they are by no means the total answer to inaccessibility. "Patching can be a very patchy business indeed, and nothing can substitute for truly inclusive design," he says. "Despite the availability of all these user tools, the ultimate responsibility for accessibility still lies firmly with the website itself."