acronym element

HTML 4 had two elements for shortened words: <abbr> for abbreviations and <acronym> for acronyms. Nobody agreed on where one ended and the other began. Is “HTML” an acronym if you spell it out letter by letter? The distinction never did anything a reader or a browser could use. HTML5 kept <abbr> and dropped <acronym>.

Why avoid

It is obsolete and non-conforming. The HTML Standard lists acronym among the elements that “are entirely obsolete, and must not be used by authors”, with a one-line instruction: “Use abbr instead.”

It does nothing <abbr> doesn’t. The Standard requires that “user agents must treat acronym elements in a manner equivalent to abbr elements in terms of semantics and for purposes of rendering”, and its default stylesheet gives abbr[title] and acronym[title] the same dotted underline. Keeping <acronym> buys no meaning. It costs a validation error on every page it appears on, and it keeps an element MDN describes as “a candidate for removal from web standards or browsers”. Default styling has varied too, with some browsers adding small caps.

Use instead

<abbr title="World Wide Web">WWW</abbr>

Because browsers already treat the two identically, swapping the tag name changes nothing a reader sees or hears. Where the expansion matters, write it out in the text on first use as well. A title is hard to reach from a touchscreen or keyboard.

Detectability

Fully detectable by tag name. There is no autofix, even though replacing acronym with abbr would be safe here. Fixes only ever remove markup, and renaming an element isn’t a removal.

Resources

• HTML Standard — Non-conforming features — acronym is entirely obsolete: “Use abbr instead.”
• HTML Standard — Other elements, attributes and APIs — user agents must treat acronym as equivalent to abbr in semantics and rendering.
• MDN — <acronym> — deprecated, a candidate for removal; use <abbr>.