<acronym> VS <abbr> - The Final Word
For many years now many developers like myself have been confused by the grey area surrounding the use of <acronym> and <abbr>. Even the specification isn’t entirely clear on the issue.
The truth is that when asked, most people have no idea on the difference between an abbreviation,, an acronym and an initialism.
Even the documents outlining what <abbr> and <acronym> do confuse the two:
ABBR:
Indicates an abbreviated form (e.g., WWW, HTTP, URI, Mass., etc.).
ACRONYM:
Indicates an acronym (e.g., WAC, radar, etc.).
Can you spot the mistakes?? Here is a nice guide to help you, maybe the document authors will take a look at it sometime.
An abbreviation is a word or phrase that has been shortened. All initialisms and acronyms are types of abbreviations.
An initialism is an abbreviation that has been shorted using the first letter of each term e.g. XHTML. Unfortunately and slightly ironically, XHTML doesn’t have an <initialism> tag, so current standard is to use the general <abbr>
An acronym is a type of initialism that can be said as a whole word e.g. Laser or Scuba. The <acronym> tag should be used for these.
When in doubt use and remember that to qualify as an acronym the term should be an initialism and you should be able to pronounce it as a whole word.