Section 1.4: Accessibility Principles

What are the 4 main accessibility principles?

In general, when thinking about accessibility the main principles to consider are: [ 27 ]

1. Web content must be perceivable
2. Interface elements in the content must be operable
3. Content and controls must be understandable
4. Content must be robust enough to work with current and future technologies

1. Perceivable:

People benefit from Web content only if they know it is there and can tell what it is. For example, users who are Deaf cannot hear audio content. Users who are blind cannot see visual content. People with reading disabilities may have difficulty decoding text when pages are crowded and busy. Thus the starting point for accessibility is to ensure that the ability to perceive content does not depend on a single sense. The methods to be used will depend on what the content is. [ 32 ]

2. Operable:

Since not everyone uses a standard keyboard and mouse, this principle highlights the need [to] allow keyboard functionality to access all content and functions (including media players) of a Web site. The keyboard control is considered most important because most alternative navigation devices either rely on the keyboard or emulate keyboard function. Operable also refers to the need to give the user multiple ways to navigate the content, i.e., using site maps or site search functions or marking the structure of the content and an ability to recover from errors. [ 31 ]

3. Understandable:

Content Change to as clear as possible, and Change to appropriate for the intended audience. It may be necessary to provide supplemental information such as brief summaries and visual illustrations. Some users may benefit from audio versions of the content. Navigation links and other functionality Change to as consistent and predictable as possible (without defeating the purpose of the site). [ 34 ]

4. Robust:

The fourth principle, robust, refers to the need to realize that people are using different kinds of technology to access Web content. They may use older operating systems, different browsers, or different versions of software. Or they may be using browsers, media players, and assistive technologies that are more recent than the content. The more control you can give the user, the better. Developers should also use valid code to help increase the chances that the site will work correctly in a variety of situations. [ 33 ]