The abbr element represents an
abbreviation or acronym, optionally with its expansion. The title attribute may be
used to provide an expansion of the abbreviation. The attribute, if
specified, must contain an expansion of the abbreviation, and
nothing else.

The paragraph below contains an abbreviation marked up with the
abbr element. This paragraph defines the term "Web Hypertext Application Technology
Working Group".

<p>The <dfn id=whatwg><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

An alternative way to write this would be:

<p>The <dfn id=whatwg>Web Hypertext Application Technology
Working Group</dfn> (<abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

This paragraph has two abbreviations. Notice how only one is
defined; the other, with no expansion associated with it, does not
use the abbr element.

<p>The
<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
started working on HTML5 in 2004.</p>

This paragraph links an abbreviation to its definition.

<p>The <a href="#whatwg"><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
community does not have much representation from Asia.</p>

This paragraph marks up an abbreviation without giving an
expansion, possibly as a hook to apply styles for abbreviations
(e.g. smallcaps).

<p>Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the <abbr>WHATWG</abbr> issue graph.</p>

If an abbreviation is pluralized, the expansion's grammatical
number (plural vs singular) must match the grammatical number of the
contents of the element.

Here the plural is outside the element, so the expansion is in
the singular:

<p>Two <abbr title="Working Group">WG</abbr>s worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Here the plural is inside the element, so the expansion is in
the plural:

<p>Two <abbr title="Working Groups">WGs</abbr> worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Abbreviations do not have to be marked up using this element. It
is expected to be useful in the following cases:

Abbreviations for which the author wants to give expansions,
where using the abbr element with a title attribute is an alternative to
including the expansion inline (e.g. in parentheses).

Abbreviations that are likely to be unfamiliar to the
document's readers, for which authors are encouraged to either mark
up the abbreviation using an abbr element with a title attribute or include the expansion
inline in the text the first time the abbreviation is used.

Abbreviations whose presence needs to be semantically
annotated, e.g. so that they can be identified from a style sheet
and given specific styles, for which the abbr element
can be used without a title
attribute.

Providing an expansion in a title attribute once will not necessarily
cause other abbr elements in the same document with the
same contents but without a title
attribute to behave as if they had the same expansion. Every
abbr element is independent.