Ensure the expanded forms of abbreviations are available to users the first time they are used or if there is any potential for ambiguity.



Example 1 — Providing the acronym after the first use
<p>The North American Free Trade Agreement (NAFTA) … </p>
Example 2 — Including the expansion using an abbr element
     title="The United States Mexico Canada Agreement"
   replaced <abbr
     title="The North American Free Trade Agreement"
   >NAFTA</abbr> in 2019 … </p>
Example 3 — Using the abbr element to differentiate similar words
<p>If you follow
   <abbr title="Saint">St.</abbr>
   <abbr title="Street">St.</abbr>
   north for ten blocks … </p>
Example 4 — Linking to a glossary entry
<p>Some <a
   are not good to expand on PG sites… </p>


Although using abbreviations and initialisms helps save space and can make for useful mnemonics, they also present a challenge for readers initially unfamiliar with the terms. This is especially problematic for individuals with cognitive and learning disabilities, who may have trouble understanding and remembering the meanings.

There are a variety of techniques that authors can use to make abbreviations and initialisms more accessible. A typical rule in most writing guides is to always provide the expanded version of the term before introducing the abbreviation in parentheses (e.g., "World Wide Web Consortium (W3C)".

This technique works best on its own when an abbreviation or initialism is only used in a small section of the work. If the term is introduced once and then repeated throughout an entire publication, however, readers will have difficulty locating its definition.

To avoid this problem, the HTML abbr element can be used to reintroduce the expansion by providing it in a title attribute (see example 2). This markup provides an unobtrusive way to tag any instance of the abbreviation.

A drawback of using the abbr element is that the expansion may only be available to users of assistive technologies. Although using the title attribute will produce a tooltip when a mouse is hovered over the abbreviation, readers may not be using a reading system with a pointing device.

Another option is to link the abbreviation to a glossary entry (see example 4). Although this option allows any user to reach the expansion, care needs to be exercised not to overload documents with links to glossary terms. The more repetitive links to a term there are in a document, the more it impedes users of assistive technologies from cycling through them. When using links, it is best to only link the first term in a section.

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