Sure, we know you put a lot of work into the design and layout of your website, but what works for some won't always work for everyone. Users with certain cognitive limitations may wish to personalize or standardize user interfaces in order to make a page more familiar and easily comprehensible. Accordingly, the rule discussed in this post asks that the purpose of user interface components, icons, and regions can be programmatically determined in cases where content is implemented with markup languages.
Those with cognitive limitations may have trouble with language skills, memory, focus, or executive function, and as a result, it can often prove overly difficult to use web pages with which they are not accustomed. By using semantics and metadata to provide context and meaning to user interface components, such as links and buttons, as well as symbols and regions, you will enable these users to render a visual display through programmatic associations that they can understand more readily.
Some users, for instance, may be more comfortable with certain icons and symbols over others. By using semantics and metadata to properly identify the components of your page, these users can swap out the labels of the links in your navigation bar with icons (such as replacing the label "Home" with a picture of a house). In addition, users may become confused by a lot of clutter on a page. When different regions on a page can be programmatically determined, these users have the option of eliminating or highlighting certain sections so they can more effectively focus.
If you've been following this blog series of ours on accessibility, you've probably seen mention of WCAG's different levels of conformance. In short, they are Levels A, AA, and AAA, each of which successively describes a higher standard of accessibility.
The criterion discussed here has been labeled AAA because it is such a comprehensive step toward achieving accessibility.