An acronym is an abbreviation you would speak as a word, for example, ROM (for read-only memory). In a spoken conversation, you would say it phonetically (Rawm) and not pronounce each letter (R-O-M). Other examples include radar and scuba, which started out as acronyms but are now considered words in their own right.
Acronyms are almost always all caps, regardless of the capitalization style of the spelled-out form.
An initialism is a type of acronym that comprises a group of initial letters used as an abbreviation for a name or expression. If you were using the acronym in a spoken conversation, you would enunciate each letter: H-T-M-L for Hypertext Markup Language or A-L-M for Application Lifecycle Management (use initial capitals in this spelled-out case as it’s an Anaplan capability).
Spell out lesser-known acronyms or initialisms on first use, then follow with the acronym or initialism in parentheses. After this, throughout the rest of your page or document, use the acronym or initialism alone.
You can use Single-Sign-on (SSO) to sign in to the Excel Add-in. You may need to ask your administrator to enable SSO.
internet service provider (ISP)
Where the acronym or initialism is more commonly used than the full phrase, for example, URL, HTML, or API, you do not need to follow this spell-it-out rule.
View also: A–Z word list and Merriam-Webster(opens external page).
Best practice: Acronyms
Which article (a or an) you use depends on whether the acronym begins with a letter that sounds like a consonant (a URL, a SQL Server database) or a vowel (an HTML table, an app).
File types and extensions
Use all caps for acronyms of file types (a JPEG file).
Filename extensions, which indicate the file type, should be in lowercase (.jpg, .xlxs).
Don't use apostrophes for plural acronyms.
Titles and headings
Avoid using an acronym for the first time in a title or heading. If the first use of the acronym is in a title or heading, introduce the acronym (in parentheses, following the spelled-out term) in the first body text that follows.
U.S., UK, and EU
In all content types, refer to the U.S. with periods, except in headings. Don't use periods in UK or EU.
Note that UK (United Kingdom) is preferable to Great Britain in most cases. UK refers to England, Scotland, Wales, and Northern Ireland, and Great Britain (GB) refers to just England, Scotland, and Wales.