The apostrophe is used to show the omission of a letter, known as a contraction, or possession.
It is not used to show plurality of any kind in any context. It doesn't matter if you're using an abbreviation or acronym. If you're not forming a contraction or showing possession, you should not be using an apostrophe.
Correct:
He's - he is
Bob's - either of: "Bob is" or showing that something belongs to Bob
they're - they are
IPs - plural of IP
ABCs - plural of ABC
Tires - plural of tire
Jackasses - people who don't use apostrophes correctly
Incorrect:
MAC's - this means nothing, it is not the plural of the acronym "MAC"
apostrophe's - this is WRONG
I can't believe how often I see incorrect use of apostrophes these days. I see it on commercial web sites, in marketing communication, in print media, etc. It's almost as bad as people who don't know whether to use "I" or "me" in the predicate of a sentence. That's a lost cause, though, as it's in literature, movies, and songs now.
tl;dr: Don't use an apostrophe if you aren't showing possession or making a contraction.
It is not used to show plurality of any kind in any context. It doesn't matter if you're using an abbreviation or acronym. If you're not forming a contraction or showing possession, you should not be using an apostrophe.
Correct:
He's - he is
Bob's - either of: "Bob is" or showing that something belongs to Bob
they're - they are
IPs - plural of IP
ABCs - plural of ABC
Tires - plural of tire
Jackasses - people who don't use apostrophes correctly
Incorrect:
MAC's - this means nothing, it is not the plural of the acronym "MAC"
apostrophe's - this is WRONG
I can't believe how often I see incorrect use of apostrophes these days. I see it on commercial web sites, in marketing communication, in print media, etc. It's almost as bad as people who don't know whether to use "I" or "me" in the predicate of a sentence. That's a lost cause, though, as it's in literature, movies, and songs now.
tl;dr: Don't use an apostrophe if you aren't showing possession or making a contraction.