The apostrophe causes more visible public mistakes than any other punctuation mark — you’ve seen it on hand-written signs: “Banana’s – $1/lb,” “CD’s for Sale.” It only has two real jobs — once you know when to use an apostrophe for each one, you’ll stop making the mistake almost everyone makes.
The 2 Real Jobs of an Apostrophe
- Possession: “the dog’s leash,” “the students’ lounge”
- Contraction: “don’t” (do not), “it’s” (it is), “they’re” (they are) — marking missing letters
That’s it. An apostrophe is never used to simply make a word plural — which is exactly where most mistakes happen.
It’s vs. Its: The #1 Apostrophe Mistake
- It’s = it is / it has (contraction). “It’s raining.”
- Its = belonging to it (possessive, no apostrophe). “The dog wagged its tail.”
The trick: if you can replace it with “it is” and the sentence still makes sense, use “it’s.” Otherwise, use “its.” This is the single most common grammar error in English writing — even professional writers slip on it.
The “Greengrocer’s Apostrophe”
This is the technical term for using an apostrophe to make a word plural — “banana’s” for more than one banana is wrong; the correct plural is simply “bananas.” An apostrophe signals possession or a contraction, never a plain plural.
Possessive Rules
- Singular noun: add ‘s — “the cat’s toy”
- Plural noun ending in s: add just an apostrophe — “the dogs’ park” (belonging to multiple dogs)
- Plural noun not ending in s: add ‘s — “the children’s books”
- Names ending in s: style-dependent — “James’s” (Chicago style) or “James'” (AP style) are both accepted. Pick one and stay consistent.
Common Mistakes
- Its/it’s confusion. The single biggest apostrophe error — see above.
- Apostrophes for plain plurals. The greengrocer’s apostrophe — “1990’s” should be “1990s,” “CD’s” should be “CDs.”
- Dropping the apostrophe in contractions. “Dont” and “wont” need one: “don’t,” “won’t.”
- Who’s vs. whose. “Who’s” means “who is”; “whose” is possessive. “Who’s coming?” vs. “Whose coat is this?”
Frequently Asked Questions
Is it “James’s” or “James'”?
Both are accepted. Chicago Manual of Style prefers “James’s”; AP Style prefers “James’.” Pick one and stay consistent.
Do plural acronyms or years need an apostrophe?
No — “CDs,” “the 1990s,” not “CD’s” or “1990’s.”
Your vs. you’re?
“You’re” is a contraction of “you are.” “Your” is possessive and never takes an apostrophe.
Quick Reference
- 2 jobs only: possession, or contraction
- Never for: plain plurals
- It’s = it is/has. Its = possessive, no apostrophe.
Quick practice: Fix the apostrophes — “Its a shame the cat lost it’s toy’s.” (Answer: “It’s a shame the cat lost its toys.”)