It is only fair that all web sites should be accessible to people with disabilities, and to the assistive devices they use to navigate the web. This post outlines key principles and resources relating to accessibility.
High Rates of Disabilities
The issue of accessibility is quite a significant one. In the US and Europe for example, nearly 20% of the population has some sort of disability, a figure that climbs to 75% in older age groups.
Visual impairment is a major form of disability and the predominant concern in effective web design. Blind users of the web typically use software that reads a web page out loud. Screen readers can read only text, not images or animations. It is important, therefore, that images and animations be given text descriptions that screen readers can read. These text descriptions are called alternative text (alt text).
Users with mobility issues may rely on the keyboard instead of the mouse to navigate web pages. In these cases, essential components of the page need to function without a mouse. Rollovers, drop-down lists, and interactive graphics frequently depend on the mouse for user interaction. The developer of these elements must ensure that keyboard-defined events function appropriately.
There are two main sources of accessibility standards.
The Web Content Accessibility Guidelines (WCAG) from the W3C represented the first major effort to establish international guidelines for accessible design. This standard consists of 14 guidelines, each with three checkpoint levels for web developers to meet: Priority One, Priority Two, and Priority Three. It is good practice for all web sites to at least comply with Priority One standards.
Individual countries also have national standards, often mandatory for web sites funded through government budgets. Most countries’ standards, such as the US, are based (at the least) on WCAG Priority One standards. Some countries (such as Canada and the United Kingdom) are based on Priority One and Priority Two standards. In some countries, non-compliance will be penalized with the loss of contract — so it is good practice, and also good business, to comply.
Priority One Checklist
Here is a partial checklist of Priority One issues:
- All graphics use alt tags
- All captions use text or alt tags
- All information conveyed in color functions without color
- Server-side maps include alternate links
- In tables, identify row and column headers
- Organize documents so they can be read without style sheets
- (Other items listed on W3C site listed below.)
Other Benefits of Accessibility Standards
In addition to providing web access to users with disabilities, attention to accessibility issues brings other advantages as well. Many accessibility principals are consistent with good web design overall. Optimized sites often download more quickly and are more efficient with low-bandwidth or outdated-browser environments. Attention to accessibility also guarantees that your site isn’t inadvertently breaking the law.
To learn more about accessibility issues, or to test sites or sub-sites for accessibility compliance, consult the following:
- Wikipedia article on Web Accessibility
- W3C Web Accessibility Initiative
- Section 508 (US Government Standards)
- Microsoft Accessibility Site