Monday, 29th May 2017 | Text only | Italiano | Español | Français | Deutsch

Web Site Accessibility

Besides meaningful content, Web developers consider intelligent design and visual impact what we call a site's overall look and feel, but all too often neglect accessibility. This means making all information accessible to a diverse group of people using different devices with a huge range of screen sizes ranging from large high-definition flat panels to small Web-enabled mobile phones and with different sensory issues and learning patterns.

One cannot simply assume the general public, let alone people with specific sensory or physical impairments, will guess how the designer intended them to navigate around a site. Many features, such as complex pop-up menus or gratuitous visual effects, may impress some visitors, but distract or impede others.

Making a web site more accessible usually means simplifying design with consistent and standards-compliant HTML code. This approach makes it easier for accessibility software such as speech synthesisers or text magnifiers to interpret the content of web pages.

Ideally all formatting information should be stored in external stylesheets and client-side scripts in external Javascript files.

Heading tags should be used to announce sections of a text, list tags for lists, blockquote tags for quotes etc.

With the advent of cascading stylesheets, tables should only be used for genuinely tabular information, but not for page layout. If possible alternative stylesheets should be available for people with different perceptions as well as for different media.

  1. Text Size: Ideally users should be able to adjust text size without text extending beyond the border of a given text area. Some designs reliant on fixed sizes preclude this option, however, if the text is of any importance this should be possible in at least one version of a page. This presents no insurmountable problem, if text is drawn from the same source, but merely uses different style sheets.
  2. Contrast: A high contrast should be maintained between text and background. Most users will prefer dark text on a light background, but be aware that many, especially those with forms of dyslexia, prefer light text on a dark background. Also some colour schemes may look radically different on different kinds of monitors, e.g. many Web sites use grey, yellow or brownish backgrounds to reduce glare on CRT monitors. Such sites may be hard to see on laptops with a TFT screen.
  3. Clear, well-formed and compatible HTML: Like it or not the only standards all web browsers understand is HTML. Make sure all essential content is human-readable and store style and scripts in separate files.
  4. Header logo leads to home: Amazingly some forget that users increasingly expect all graphic elements to do something. Note only should Home be the first item in the main menu, but the main logo should also lead back to the home page. If a site is complex, consider breadcrumbs.
  5. Minimise junk: Ideally keep style and Javascripts in separate linked files to make web pages as human-readable as possible. Replace in-line "onclick" or "onmouseover" event handlers with id elements refenced by a separate Javascript method.
  6. Printable: Offer a printable version of pages. This can easily be done by linking a page to a Javascript that instructs the browser to print the body of page without the header or menu and neatly aligned within page borders. By default background images will not be printed and text within fixed elements, may often extend beyond the edge of a page.
  7. Media descriptions: Always offer text alternatives to pictures, video or audio.
  8. Keyboard friendly: Use access keys in links to the main areas of your site to enable users without access to a mouse to use a keyboard shortcut. This is probably one of the most overlooked features of HTML 4.0 +.
  9. HTML is king: All information should be available in standards-compliant HTML. Alternative Web formats such as PDF and Macromedia Flash should only be used to preserve the original formatting of source documents or obtain effects and interactivity that current XHTML, CSS and Javascript standards do not allow. Well-designed web pages with alternate print stylesheets are already print-friendly. For instance no accessible site should state “For more information, please download our PDF report”, but rather “For more information, please read our report (also available as a PDF file).”
    PDF is excellent medium for graphics-rich newsletters, books, manuals, presentations and reports. However, PDF conversions from proprietary formats (see below) often produce mediocre results and significantly larger file sizes than an HTML equivalent. Ideally PDF files should be created by vector graphics applications that support the format natively   leading to smaller file sizes and a more polished and scalable appearance.
    Adobe Flash is a Web-optimised format that extends the Web's multimedia potential. However, it remains a proprietary plug-in practically invisible to search engines. The W3C has recommended use XML-based SVG (Scalable Vector Graphics) and SMIL (Synchronized Multimedia Integration Language) for vector graphics, animations, audio and video. Currently few Web sites have adopted this format, but Adobe Acrobat Reader includes SVG Player 1.0, so a very high percentage of surfers already have a requisite plug-in, but in the long term the user-agents (browsers) should support it natively.
  10. No non-Web formats: Avoid using proprietary word-processor, spreadsheet, presentation, desktop-publishing   formats such as Microsoft Word, Excel, Power Point or Publisher. Convert such information first to HTML. Such formats not only rely on an application external to the browser, which even if present requires additional processing resources, but are nearly always much larger. Word processors are essential home and office workhorses, but since 1997 all have offered an HTML export facility, which any good HTML editor can then clean up before publication. However, some documents such as application forms may need to be downloaded, edited and returned in the same format. In this case the most accessible format is RTF (rich text format) compatible with all major word processors.

Accessibility Links

W3C Accessibility Initiative
"The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect." Tim Berners-Lee, W3C Director and inventor of the World Wide Web
Ebility:
This site offers easy access and links to a wide range of information, resources, services and products of interest to people with disability, their families and carers, as well as health professionals and other service providers in the disability sector.
Bobby:
This tool analyses web pages for their accessibility to people with disabilities.

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