Acronyms are words formed from the initial letters of a multiword term. These can be names of organizations (NATO), nations (USA), and phrases (FAQ). While acronyms are highly efficient, care needs to be taken when using them. Too many, the AP Style Guide warns, produces “alphabet soup.”
Acronyms that are widely and immediately understandable by the vast majority of your audience can be used without prior definition: “The FBI said it was working on the case.” If the term is less commonly known, it should be initially used in full (“The attorney general questioned the project’s return on investment”); thereafter, the acronym can be used (“The project’s ROI was questioned”).
If the acronym is unlikely to be known by a large number of readers, yet doesn’t appear frequently enough in the story to become familiar, one approach is to use the term in full with the acronym in parentheses immediately afterward: “The National Association of Manufacturers (NAM) denounced the bill.” Thereafter, the acronym can be used alone.
Note that if you’re only going to use an unfamiliar acronym once, it’s best just to spell out the original term completely and forgo the abbreviated form. As the AP Style Book writes, “Names not commonly before the public should not be reduced to acronyms solely to save a few words.”
Guard against following an acronym with a word that appears in the acronym itself: TARP stands for “Troubled Asset Relief Program,” so writing “The TARP program was controversial” is redundant.
Most acronyms should be used without periods: “The USA was eliminated in the second round of the tournament.” However, handled this way, many two-letter acronyms could spell out unrelated words — United Nations would become “UN” — so it’s best to use the punctuated form: U.N., U.S., U.K. and so forth.
Somewhat of an exception are academic degrees, which get the following punctuation and capitalization: B.A. (bachelor of arts); B.S. (bachelor of science); M.A. (master of arts); M.S. (master of science); M.B.A. (master of business administration); and Ph.D. (doctorate).
While acronyms are all formed from some combination of the first letters or parts of words, how they’re treated differs. For example, “scuba” is technically an acronym, but since being coined it has become a word in its own right, no capitalization required.
A related trend is lowercasing the first letter of “small” words such as “of.” This is seen in MoMA (Museum of Modern Art) as well as PoC (proof of concept) and CoP (community of practice). These treatments clue readers in to what the acronyms stand for and prevents them from reading something like COP as a verb or a noun. Note the distinction between acronyms and initialisms: “FBI” is an initialism because it’s pronounced as the letters that make it up; “NASDAQ” (National Association of Securities Dealers Automated Quotations) is a true acronym — it’s pronounced like a word.
To indicate plurals of acronyms, simply add an “s” without an apostrophe: “She was addicted to finding new MP3s.” The single exception is if the term being pluralized has periods in it. In this case, use an apostrophe and an “s” for clarity: “At least a dozen M.D.’s showed up for free sushi.”
Acronyms are given indefinite articles based on how they’re pronounced, not how they’re spelled: “a URL” (sounded as “yu”); “an HTTP protocol” (sounded as “aitch”); “an MS application” (sounded as “em”).