Web accessibility refers to the practice of making websites usable by people of all abilities and disabilities. When sites are correctly designed, developed and edited, all users can have equal access to information and functionality. For example, when a site is coded with semantically meaningful HTML, with textual equivalents provided for images and with links named meaningfully, this helps blind users using text-to-speech software and/or text-to-Braille hardware. When text and images are large and/or enlargable, it is easier for users with poor sight to read and understand the content. When links are underlined (or otherwise differentiated) as well as coloured, this ensures that colour blind users will be able to notice them. When clickable links and areas are large, this helps users who cannot control a mouse with precision. When pages are coded so that users can navigate by means of the keyboard alone, or a single switch access device alone, this helps users who cannot use a mouse or even a standard keyboard. When videos are closed captioned or a sign language version is available, deaf and hard of hearing users can understand video. When flashing effects are avoided or made optional, users prone to seizures caused by these effects are not put at risk. And when content is written in plain language and illustrated with instructional diagrams and animations, users with dyslexia and learning difficulties are better able to understand the content. When sites are correctly built and maintained, all of these users can be accommodated while not impacting on the usability of the site for non-disabled users.
The needs that Web accessibility aims to address include:
- Visual: Visual impairments including blindness, various common types of low vision and poor eyesight, various types of colour blindness;
- Motor/Mobility: e.g. difficulty or inability to use the hands, including tremors, muscle slowness, loss of fine muscle control, etc., due to conditions such as Parkinson’s Disease, muscular dystrophy, cerebral palsy, stroke;
- Auditory: Deafness or hearing impairments, including individuals who are hard of hearing;
- Seizures: Photoepileptic seizures caused by visual strobe or flashing effects.
- Cognitive/Intellectual: Developmental disabilities, learning disabilities (dyslexia, dyscalculia, etc.), and cognitive disabilities of various origins, affecting memory, attention, developmental “maturity,” problem-solving and logic skills, etc.;
- Clark, Joe (2003). Building Accessible Websites. New Riders Press. ISBN 0-7357-1150-X.
- Thatcher, Jim; Cynthia Waddell, Shawn Henry, Sarah Swierenga, Mark Urban, Michael Burks, Paul Bohman (2003). Constructing Accessible Web Sites, Reprint, Apress (Previously by Glasshaus). ISBN 1-59059-148-8.
- Slatin, John; Sharron Rush (2002). Maximum Accessibility: Making Your Web Site More Usable for Everyone. Addison-Wesley Professional. ISBN 0-201-77422-4.
- Paciello, Michael (2000). Web Accessibility for People with Disabilities. CMP Books. ISBN 1-929629-08-7.
- Bangeman, Eric. “Judge: ADA lawsuit against Target can proceed“, Ars Technica, 2006-09-10. Retrieved on 2006-09-26.
Standards and guidelines
- The main page for the W3C’s Web Accessibility Initiative (WAI)
- Wikipedia accessibility guidelines
- Illinois HTML/xhtml Accessibility Best Practices
- New York State Mandatory Technology Standards for Accessibility of State Agency Web-Based Intranet and Internet Information and Applications – Fourteen standards derived from both U.S. Section 508 and the WAI’s WCAG 1.0 and required for NYS agency web sites.
- Americans with Disabilities Act Section 508 Guidelines and Section 508 Homepage
- Index of government guidelines – Searchable catalog of international web accessibility guidelines.
- Disability Discrimination Act UK
- Section 508 – requires U.S. government web sites to be accessible
- New York State Technology Policy P04-002 – Requires Accessibility of State Agency Web-Based Intranet and Internet Information and Applications, requires all State entity web sites to be accessible according to NYS standards which are a hybrid of Section 508 and the W3C’s WCAG 1.0. Updates Statewide Technology Policy 99-3, which required sites to conform to the W3C WCAG 1.0, Priority one checkpoints only.
- Disability Act 2005 Ireland
Resources for users
- American Foundation for the Blind – Web Accessibility
- The National Library for the Blind’s Web Accessibility page
- Royal National Institute of the Blind: Technology
- My Web My Way from the BBC
Resources for designers
- Accessibility101 – UK Web Accessibility FAQ
- Accessibility Advice from The National Library for the Blind (NLB)
- Accessibility at Web Design Reference – A large online reference dedicated web design and development
- National Disability Authority (Ireland) – ICT Accessibility
- RNIB Web Access Centre
- Why W3C Compliant? The Importance of Valid Web Codes by Mihaela Lica
- Accessibility Statement generator by Rio Akasaka
- Unified Web Evaluation Methodology
- Just Ask: Integrating Accessibility Throughout Design from Shawn Lawton Henry
- Section 508 Training Courses (free!)
- System X Accessible Captcha system – textTHaCAA PHP based Accessible Captcha system available under the LGPL
Web accessibility checkers
- W3C’s database of Web Accessibility Evaluation Tools – revitalised in early 2006 and regularly updated
- Functional Accessibility Evaluator – Test websites for use of CITES/DRES HTML/xhtml best Practices to implement Section 508 and W3C WCAG accessibility requirements
- WAVE – Web Accessibility Versatile Evaluator
- Basic Accessibility Check – Web based tool with tests that all web pages should pass. Based on the Ruby Accessibility Analysis Kit.
- TAW – Web Accessibility Test – Tool for the accessibility analysis of Web sites, based on the W3C – Web Content Accessibility Guidelines 1.0 (WCAG 1.0)
- Text-only browser emulation – Tool for accessibility evaluation by emulating the Lynx text-only web browser (LynxViewer at yellowpipe.com); Alternative Text-only browser emulator hosted at pizzaseo.com (some limitations as of March 2007).
- Truwex Online, Web Accessibility Validation Tool – The tool validates a web page and displays results on a web page screenshot.
Disability/Impairment Simulators and Other Tools
- GrayBit – Grayscale Conversion Contrast Accessibility Tool
- Colour Contrast Analyser 1.1 A tool for checking foreground & background colour combinations to determine if they provide good colour visibility.
- Colour Contrast/Difference Analyser Tool that shows HTML/CSS tree with elements not passing colour contrast test.
- Colorblind Web page filter
- Vischeck color deficit emulation
- WebAIM Disability Simulations – Simulation for screen reader access, visual disabilities, dyslexia, and distractibility.
- Fangs screen reader emulator – A Mozilla Firefox extension that simulates how a web page would look in a screen reader.
Web browser accessibility features
- Internet Explorer 6 Accessibility Resources
- Mozilla Accessibility Project (includes Firefox)
- Mozilla/Firefox Accessibility Extension
- Accessibility in the Opera web browser