Layers of Guidance: How to Use the Web Content Accessibility Guidelines (WCAG) 2.0

As the name suggests, the Web Content Accessibility Guidelines (WCAG) 2.0 are a set of guidelines developed “with a goal of providing a single shared standard for web content accessibility that meets the needs of individuals, organizations, and governments internationally.”[1] Designing and producing content for individuals who live with disabilities can be difficult. What is accessible for one person may prove inaccessible for another; also, such content may be inaccessible to the same person, depending on the situation–whether he or she is accessing information from a laptop or from a smartphone or tablet, for example.

Compounding the issue of web accessibility is the traditional lack of useful guidance for developers and content managers. Legislative pieces, such as Section 508 of the Rehabilitation Act of 1973, come down to little more than proscriptive checklists: they lay out what needs to be done according to a set of fixed technical standards; however, they do not attempt to define what accessibility means for actual users, nor do they offer any real guidance for how to achieve that accessibility.

WCAG, and especially its revisions in version 2.0, is designed to address such shortcomings by defining what “accessible” content is, presenting guidelines in such a way that they can be easily understood and adapted to new technologies, and offering a wealth of techniques and examples for making content accessible.

Overview

For content to be considered accessible, according to WCAG 2.0, it must meet four principles: Perceivable, Operable, Understandable, and Robust (POUR).

• Perceivable: The user must be able to perceive the information and user interface elements. This often requires information to be presented in multiple formats. For example, for users with visual disabilities, images must include alternative text.
• Operable: The user must be able to navigate the content successfully and be able to make use of all its features. For example, a keyboard-only user must be able to navigate all fields in a form without becoming “trapped” within any one.
• Understandable: The user must be able to understand the information presented and the user interface components. For example, information should be presented in easily digestible sections to accommodate users with cognitive disorders.
• Robust: Content must be accessible by a wide variety of user agents, including browsers and assistive devices, as screen readers. Robustness also includes the need to keep up with new technologies and new methods of access. For many users today, both disabled and non-disabled, this includes the shift from PCs to mobile devices.[2]

The heart of WCAG 2.0 are the Guidelines. Looking at the documentation for the first time, it may seem overwhelming–having to determine what guidelines need to be met and how to go about meeting them. Fortunately, WCAG 2.0 is structured to provide “layers of guidance”[2] that follow, one under the other, while maintaining clear navigational points thanks to the use of HTML. WCAG 2.0 documentation is available in a number of formats, including PDFs; however, it is recommended user approach it as a “live” document on the Web to make the most of this structure.

The four layers of guidance are:

• Principles: As discussed above, the four principles of what makes content accessible (POUR) are the starting point for the Guidelines themselves.
• Guidelines: The Guidelines are essentially accessibility goals. As the WCAG 2.0 documentation notes, they are not themselves “testable, but provide the framework and overall objectives” to understand and apply the remaining two layers.
• Success Criteria: The Success Criteria are the testable portion of WCAG 2.0. They can be used in conformance testing–both automatic and manual/human-based–and are divided into three conformance levels: A, AA, and AAA. AA has become the standard for most businesses and organizations.
• Sufficient and Advisory Techniques: These techniques are documented ways to reach particular Success Criteria and Guidelines. They are not the only way Success Criteria can be met; however, they can form the basis of solid best practices. Techniques are divided into two categories: Sufficient and Advisory. Sufficient Techniques have been shown to meet the Success Criteria. Advisory Techniques go above and beyond the Success Criteria in some way to further improve access.[2]

Example

It is beyond the scope of this blog post to detail all of the Guidelines and Success Criteria found in WCAG 2.0; however, an example will suffice to illustrate the structure of the document. Use the links in the following paragraph to move through the document layer by layer.

Adding alternative text to images and other non-text objects is a basic practice in web accessibility. Here, it falls under the the Perceivable Principle and is covered by Guideline 1.1 Text Alternatives. The relevant Success Criteria is SC 1.1.1 Non-text Content, and it can be addressed by these Non-text Content Techniques.

For more information, please refer to WAI-W3C’s WCAG Overview and WebAIM’s Web Content Accessibility Guidelines overview.