Mark up term-and-definition pairs as description lists
A description list, built from dl, dt and dd, tells software that a run of items are pairs. W3C's own reason for the technique is a glossary. It attaches H40 to 3.1.3 Unusual Words, which sits at Level AAA, and lists it as sufficient only in combination with the general technique of linking terms to their definitions. So this is the markup half of a glossary rather than a rule about every label and value on your site. Use it for glossaries, for question-and-answer pairs, and for label-and-value metadata. Styled divs look identical and carry no pairing underneath at all. Two markup rules people trip over. Several terms may share one description and one term may take several descriptions, and terms sharing a description have to follow each other with nothing in between.
How we find it in an audit
We can check an existing description list against those markup rules in a second. What no tool can do is spot the glossary that was built from divs, because recognizing that two lines are a term and its definition is a reading job. So we look at pages with visible term-and-definition pairs and listen to what a screen reader makes of them.
How affected users experience it
A real description list announces itself, says how many items it holds, and keeps every term attached to its own definition, so a listener can move term to term and stop at the one they came for. The div version arrives as an undifferentiated run of short lines. With two entries you can hold that in your head. With 40 you cannot, and the page has quietly turned into a memory test.
Passes vs. fails
Passes
<dl>
<dt>Latency</dt>
<dd>Delay before a transfer of data begins</dd>
</dl>Fails
<div class="term">Latency</div>
<div class="def">Delay before a transfer of data begins</div>Other ways to satisfy this rule
7 guides on this site are filed under 3.1.3 Unusual Words. W3C lists this one as sufficient for that rule only alongside G55, so the pair is what passes and neither half does on its own.
- G55sufficientLink unusual words to their definitions
- G62sufficientProvide a glossary for specialized terms
- G70sufficientOffer a dictionary search for specialized content
- G101sufficientDefine words used in an unusual or restricted way
- G112sufficientDefine specialized terms inline where they appear
- H54sufficientMark the defining instance of a term with dfn
This guide is our interpretation of W3C technique H40: Using description lists. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.