Abbreviations
What this means
When a page uses an abbreviation, acronym, or initialism, a way to find its expanded meaning needs to be available. This can be a glossary, a link to a definition, or markup like the HTML `<abbr>` element with a `title` attribute. Abbreviations that have become everyday words, such as "laser," or well-known names like "IBM," don't need this treatment, since most readers already recognize them.
Who it affects
People with cognitive disabilities benefit most from having abbreviations spelled out. So do people with limited working memory, or trouble decoding unfamiliar text. An acronym that's obvious to someone in a specific field can be meaningless to a general reader. Without a way to check its meaning, that reader is stuck guessing, or has to go search elsewhere for the answer. This also helps anyone unfamiliar with a given industry's shorthand, since jargon-heavy abbreviations rarely explain themselves.
Code example
Bad
<!-- No way to find out what WCAG stands for -->
<p>This site follows WCAG guidelines for accessibility.</p>Good
<!-- The abbr element's title attribute provides the expanded form -->
<p>This site follows
<abbr title="Web Content Accessibility Guidelines">WCAG</abbr>
guidelines for accessibility.</p>How to test it
Scan the page for abbreviations, acronyms, and initialisms that aren't already common household terms. For each one, check whether its expanded meaning is available somewhere, through an `<abbr>` element, a glossary, or a nearby explanation. If an abbreviation appears with no way to determine its meaning, this fails.