Understanding WCAG 2

Web Content Accessibility Guidelines (WCAG)

The Web Content Accessibility Guidelines (WCAG) documents explain how to make Web content accessible to people with disabilities.
Web "content" generally refers to the information in a Web page or Web application, including text, images, forms, sounds, and such.
WCAG is part of a series of accessibility guidelines, including the Authoring Tool Accessibility Guidelines (ATAG) and the User Agent Accessibility Guidelines (UAAG).

Who is WCAG for?

WCAG is primarily intended for:

Web content developers (page authors, site designers, etc.)
Web authoring tool developers
Web accessibility evaluation tool developers
Others who want or need a technical standard for Web accessibility

WCAG and related resources are also intended to meet the needs of many different audiences, including people who are new to Web accessibility, policy makers, managers, and others.

WCAG Versions: 1.0 and 2.0

History

Web Content Accessibility Guidelines 1.0 was published in May 1999.
WCAG 2.0 was published on 11 December 2008.
WCAG 2.0 applies broadly to more advanced technologies
WCAG 2.0 is easier to use and understand
WCAG 2.0 is more precisely testable with automated testing and human evaluation.

Most Web sites that conform to WCAG 1.0 will not require significant changes in order to conform to WCAG 2.0, and some may not need any changes.

What is in WCAG 2.0

WCAG 2.0 has 12 guidelines that are organized under 4 principles:

perceivable,

operable,

understandable,

and robust.

For each guideline, there are testable success criteria, which are at three levels: A, AA, and AAA.

Principle #1

Perceivable

Provide text alternatives for non-text content. [Text Alternatives]
Provide captions and alternatives for audio and video content. [Time Based Media]
Make content adaptable; and make it available to assistive technologies. [Adaptable]
Use sufficient contrast to make things easy to see and hear. [Distinguishable]

Text Alternatives

Explanation

http://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv.html

Success Criteria

Examples, Techniques, Failures

http://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv-all.html

For Example: Provide text alternatives for non-text content.

Guideline 1.1: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.

Situation A: If a short description can serve the same purpose and present the same information as the non-text content:

http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G94

Another Example: Make content adaptable; and make it available to assistive technologies.

Guideline 1.3: Create content that can be presented in different ways (for example simpler layout) without losing information or structure.

Example 2: CSS is used to position a navigation bar, the main story on a page, and a side story. The visual presentation of the sections does not match the programmatically determined order, but the meaning of the page does not depend on the order of the sections.

http://www.w3.org/TR/UNDERSTANDING-WCAG20/content-structure-separation.html

Principle #2

Operable

Make all functionality keyboard accessible. [Keyboard Accessible]
Give users enough time to read and use content. [Enough Time]
Do not use content that causes seizures. [Seizures]
Help users navigate and find content. [Navigable]

For Example: Help users navigate and find content.

Guideline 2.4: Provide ways to help users navigate, find content, and determine where they are.

Example: A short article about the history of a town that explains about the founding and expansion of the town and then goes into some depth about the current situation. The title of the Web page is "History of Ourtown". The first section is called "The founding of Ourtown". The second section is called "Expansion of Ourtown". The third section is called "Ourtown today" which has the following subsections: "People in Ourtown", "Organizations in Ourtown" and "Buildings in Ourtown".

http://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-descriptive.html

Visualizing navigation by Headers

Screen Reading Technology can allow users to navigate a page by Headings.

Principle #3

Understandable

Make text readable and understandable. [Readable]
Make content appear and operate in predictable ways. [Predictable]
Help users avoid and correct mistakes. [Input Assistance]

For Example: Make text readable and understandable.

Guideline 3.1: Make text content readable and understandable.

Example: An abbreviation whose expansion is provided the first time the abbreviation appears in the content. The name, "Stanford University School of Education" appears as the first heading on the organization's home page. The abbreviation, "SUSE," is enclosed in parentheses in the same heading.

http://www.w3.org/TR/UNDERSTANDING-WCAG20/meaning-located.html

Principle #4

Robust

Maximize compatibility with current and future technologies. [Compatible]

For Example: Make text readable and understandable.

Guideline 4.1: Maximize compatibility with current and future user agents, including assistive technologies.

Example: Name, Role, Value (ARIA): For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

http://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-rsv.html