Web accessibility
What is web accessibility?
Not everyone who accesses the internet uses the same technology. The variety of different computers, browsers and speeds of connection is incredible. Likewise, the abilities that visitors to websites have are also wide ranging. To assist the diverse range of abilities users have, various techniques in web design have been developed, called web accessibility.
Web accessibility is 'ensuring that web sites will be usable and available to the largest possible number of readers, visitors and customers'. Jeffrey Zeldman, designing with web standards.
Grades of accessibility
To help developers build accessible websites there are three grades of accessibility, as measured by the Web Accessibility Initiative (WAI), the governing body for accessibility standards on the web.
- Level1:
This level covers things such as ensuring all images have descriptions for people who are visually impaired or blind. These descriptions are known as an ALT tag, which stands for alternative text for the image. - Level 2:
This level covers such things as level of contrast between the text colour and the pages background colour. It also requires that there is no blinking text. These techniques ensure that users with visual impairments are not disadvantaged. - Level 3:
This level requires that users can use the tab key to move through the page. So if there is a list of links the tab key can be used to navigate to the link the user wants. Also if there is a form to be filled in, say an application form, the user should be able to use their tab key to move the cursor into each box on the page and fill in their details. This is to help people who cannot use computer mice and rely on keyboards or other assistive devices to navigate around pages and websites.
Structuring information for accessibility
However, web accessibility it not just about the technical construction of the page; it also encompasses the structure of information.
- Does the page read in a logical and sensible way?
- Is it clear on every page where you are in relation to the entire site?
- Are there methods available to quickly get to the home page?
- Can I alter the size of the text?
- Can I fill in any forms on the page without using a mouse?
If the answers to these questions are yes, then it is likely to be a fairly accessible website. If the answers are no then some work will be required.
Useful links
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Information on web usability for people with disabilities. Part of the World Wide Web Consortium (W3C) website.
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The Web Standards Project is a grassroots coalition fighting for standards that ensure simple, affordable access to web technologies for all.
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This site explains why and how to make web pages more accessible.
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Information about Cascading Style Sheets (CSS) and the web authoring language XHTML.
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A demonstration of what can be accomplished visually through CSS design.
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This Style Guide for the Branch Libraries of the New York Public Library explains the markup and design requirements for all Branch Libraries web projects, along with various standards and best practices.
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The W3C CSS Validation Service; a free service that checks Cascading Style Sheets (CSS) in (X)HTML documents or standalone for conformance to W3C recommendations.
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A number of tutorials on web technologies including CSS and XHTML.
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The Web Accessibility Toolbar has been developed to aid manual examination of web pages for a variety of aspects of accessibility.
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A tool that blends colours and provides colour valurs that can be used in a style sheet.
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The popular Mozilla Firefox browser can be downloaded here.
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The Opera browser can be downloaded here.
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Acrobat solutions for accessibility - information on increasing the accessibility of both the Adobe Acrobat software and the information included in Adobe Portable Document Format (PDF) files.
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Accessibility information from IBM - how to make your organization more accessible to citizens, employees and other businesses.