I’ve always known that an acronym is a collection of letters used as shorthand for a longer name or title. They’re all around us. ASAP, PS, IBM, DPI … and the more recent additions like LOL or BTW. What I didn’t know is that acronyms are actually words you pronounce as a word while the ones you say each letter are properly known as initialisms. So if you say A-sap, then it is an acronym but if you say A-S-A-P then it is an initialism. Good to know if this ever comes up on Jeopardy, eh?
What drives me crazy is the addition of an apostrophe when the plural form of an acronym is needed. The apostrophe is used to represent possession or that something is missing. Thus “the FBI’s nifty bullet-proof vests” is correct because those vests belong to the the FBI. But you wouldn’t use an apostrophe to say “the IMBs of the world” because we’re using the acronym in the plural.
As for periods between the letters, like C.I.A., don’t. Most all style guides either ban them or make them optional. Much neater without the periods.
A final note of caution. Don’t use an acronym if you’re unsure of the meaning. Might be better to check with a youngster! You’ve all heard of the new-to-texting grandma who sent a message around to family and friends announcing the passing of a relative, and ended her message with LOL? She thought it meant “Lots of Love”. Oops!
A painless way to get the real scoop on grammar and punctuation rules can be found at Grammar Girl’s website.