Understandable · 3.1 Readable
A mechanism must be available to identify the specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon, such as inline definitions, links to definitions, or a glossary.
Live demo
The same task, done two ways: switch between the version that passes and the one that fails, or put them side by side. Everything in the box is live, so try it with a keyboard, a pointer or a screen reader.
Read both versions in the screen reader preview, then open the Links view. Only the passing version links each unusual term to its meaning.
The monthly cost below is a ballpark figure. Your loan ends with a balloon payment in year five.
Monthly cost: $1,240
The monthly cost below is a ballpark figure. Your loan ends with a balloon payment in year five.
Monthly cost: $1,240
The tools follow the version you last used.
What happened
Why it passes
Each unusual term is a link to a short definition, so a reader who does not know the idiom or the jargon can look it up and come back.
Why it fails
The idiom and the lending jargon appear with no explanation, so a reader who does not know them has to guess what the offer means.
Examples
Four examples, each one running: the usual ways this criterion fails, and code that passes. Listen to them, measure them, or copy the code.
Fails
Live preview
<p>The monthly cost below is a ballpark figure. Your loan ends with a balloon payment in year five.</p>"Ballpark figure" is an idiom and "balloon payment" is lending jargon. Readers who do not know them have no way to find out what they mean here.
Passes
Live preview
<p>The monthly cost below is a <a href="#ballpark">ballpark figure</a>. Your loan ends with a <a href="#balloon">balloon payment</a> in year five.</p><h2>Words used in this offer</h2><dl> <dt><dfn id="ballpark">Ballpark figure</dfn></dt> <dd>A rough estimate, not the exact amount you will pay.</dd> <dt><dfn id="balloon">Balloon payment</dfn></dt> <dd>One large payment at the end of a loan that clears everything still owed.</dd></dl>Each term links to its definition in a glossary on the same page, so readers can check the meaning and come back to the offer.
Fails
Live preview
<p>Your deposit is held in escrow until the sale is complete.</p>"Escrow" is legal jargon that many home buyers do not know, and nothing on the page explains it.
Passes
Live preview
<p>Your deposit is held in <dfn>escrow</dfn>, which means a neutral company keeps the money until the sale is complete.</p>The dfn element marks the term and the rest of the sentence defines it, so no one has to leave the text to understand it. This combines inline definitions with technique H54.
Why it matters
People with cognitive, language, or learning disabilities, non-native speakers, and readers whose first language is a sign language may not understand idioms, jargon, or specialized word meanings. Definitions let them follow the intended meaning.
W3C: Understanding 3.1.3Level AAA
Level AAA is the highest level. It is not required for whole sites, but it is worth meeting where you can.
Where it is required
No law on this site requires Level AAA criteria for whole sites.
How to test
A few concrete steps. Automated tools find some failures; most need a person.
Common failures