HTML and CSS Reference
In-Depth Information
Web coding and markup is a critical part of removing barriers. But done incorrectly, it
can erect more barriers.
The hardware and software used to access web content constitute the rest of the solu-
tion. The user agent, such as a browser, and any assistive technology, such as a screen
reader that reads aloud web content, must be able to accurately interpret and present
to users the web content or functionality that you have coded.
Accessibility Guidelines
Fortunately, there are published guidelines to provide direction to web designers and
developers. If you work on government or publicly funded websites, you may imple-
ment local or federal guidelines such as U.S. Section 508.
You may also be familiar with phrases like the W3C Web Accessibility Initiative
(WAI) or W3C Web Content Accessibility Guidelines (WCAG). The W3C WAI
updated the original WCAG. WCAG 2.0 became a W3C recommendation in December
2008, nine years after the first version was released. These guidelines provide an inter-
national set of recommendations on how to make web content more accessible and
usable to people with a variety of disabilities.
WCAG 2.0 uses the acronym POUR to summarize the four principles of web accessi-
bility. POUR stands for Perceivable, Operable, Understandable, and Robust:
Perceivable
Means that the content is available to the senses, usually sight or hearing. That
means you've done things like provide text alternatives for images, provide
captions for audio and video, and include sufficient contrast between the text and
the background.
Operable
Ensures that people can use or interact with the website, including navigation,
content, forms, and dynamic controls.
Understandable
Means that the text is legible and the site behaves in consistent, predictable ways.
Robust
Defines the page's markup and coding as working in a variety of user agents and
assistive technologies.
The W3C WAI also authored WAI-ARIA 1.0 (Accessible Rich Internet Applications).
ARIA provides a way to add semantic meaning to Ajax-like, dynamic web content and
custom widgets by defining a set of roles and the states and properties of those roles.
In other words, ARIA allows you to programmatically communicate to assistive tech-
nologies what is displayed to sighted users as the page changes in response to user
actions, rather than just what is present in the original page markup.
