Acronyms vs. Initialisms: What’s the Difference?
  • 4-minute read
  • 3rd April 2022

Acronyms vs. Initialisms: What’s the Difference?

Acronyms and initialisms are two types of abbreviation that typically consist of the first letter of each word in a phrase. The key difference between them is that we pronounce acronyms as a word and initialisms as a list of letters.

This post will explain the rules you should follow when using initialisms and acronyms in your writing.

What is an Acronym?

An acronym is an abbreviation of a phrase created by using the first letter of each word (or some of the words) in the phrase. The acronym is then pronounced as the word or sound that these letters spell out. Here are some well-known examples of acronyms:


FLOTUS (First Lady of the United States)


NATO (North Atlantic Treaty Organization)


BAFTA (British Academy of Film and Television Arts)


Acronyms are normally written in capital letters, although some British style guides recommend capitalizing only the first letter (e.g., Unicef). It isn’t usually necessary to use any punctuation, but in US English, it is acceptable to punctuate acronyms with a period after each letter if you wish to. In addition, some style guides insist on including periods. Whether you punctuate or not, be sure to be consistent throughout your document.

Several acronyms have become accepted as words in their own right. Examples include scuba (self-contained underwater breathing apparatus) and gif (graphics interchange format). When you use this kind of acronym, you should treat it like a regular word by writing it in lowercase letters.

What is an Initialism?

Like acronyms, initialisms are abbreviations created by using the first letters of each word in a phrase. However, initialisms are pronounced as a list of letters, not as a word:


FBI (Federal Bureau of Investigation)


VPN (Virtual Private Network)

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BBC (British Broadcasting Corporation)


Initialisms are always written in capital letters, and, like acronyms, they only need periods after each letter if you’re following a style guide that requires them.

In most cases, initialisms are preceded by an article (i.e., a, an, or the). For instance:


I hope to become an FBI special agent.

The BBC received many complaints about the show.


However, there are various exceptions to this rule—for example, substances (e.g., LSD) and medical conditions (e.g., RSI). Check out our earlier blog post for more info on using articles with acronyms and initialisms.

How to Introduce Acronyms and Initialisms

When you first introduce an acronym or initialism in a piece of writing, you should use the full phrase followed by its abbreviation in parentheses:

The Royal Society for the Protection of Birds (RSPB) was founded in 1889.

From there on, you can use the acronym alone:

By 2020, the RSPB had over one million members.

However, if you are confident that your readers will already be familiar with the abbreviation (e.g., UFO, TV), there’s no need to spell out the full version.

Summary: The Difference Between Acronyms and Initialisms

Acronyms and initialisms are abbreviations formed by using the first letter of each word in a phrase. However, acronyms are pronounced as a word (e.g., PIN), whereas initialisms can’t easily be pronounced as a word, so instead, they are spoken as a list of letters (e.g., DVD).

Both of these types of abbreviations are typically written in capital letters without punctuation unless your style guide says otherwise. Be aware that some acronyms are now treated as ordinary words (e.g., scuba, gif, and radar).

After this post, we hope you feel confident about using acronyms and initialisms in your writing. If you’d like an expert to check your writing for flawless grammar and spelling, our proofreaders are just a few clicks away. Why not send us 500 words for free and find out how we can help?

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