Apostrophe Rules: Possessives, Contractions, and Common Errors

That tiny curled mark does a lot of heavy lifting. Apostrophe rules sound straightforward on paper — mark possession, or stand in for missing letters — but something about them still trips up native speakers, professional writers, and every bakery that ever chalked "fresh donut's" on a sidewalk sign. Errors show up in menus, memos, tattoos, and national newspapers.

The good news is that almost every apostrophe question can be settled with a short checklist. This guide walks through each situation where the mark earns its keep, including the edge cases that seem to give everyone trouble.

What Is an Apostrophe?

An apostrophe (') is a punctuation mark with two jobs in English: it signals that something belongs to someone or something, and it shows that one or more letters have been dropped from a word. Despite the creativity of shop signs across the English-speaking world, it does not turn a singular noun into a plural.

Showing Who Owns What

A Single Owner

When one person, animal, or thing owns something, attach an apostrophe plus the letter "s" to the owner:

• "the pilot's headset" (the headset that belongs to the pilot)
• "Maya's bicycle" (the bicycle belonging to Maya)
• "the restaurant's menu" (the menu of the restaurant)
• "the kitten's blanket" (the blanket belonging to the kitten)

The same pattern holds even when the owner already ends in "s":

• "Thomas's jacket"
• "the witness's testimony"
• "Dickens's first novel"

A note on style: AP style drops the trailing "s" after a singular name that already ends in the letter, giving you "Thomas' jacket" instead of "Thomas's jacket." Chicago and most academic style guides keep the "'s." Either form is defensible; pick one and stick with it throughout a piece.

Multiple Owners

When a plural noun already ends in "s," all you need is a trailing apostrophe:

• "the pilots' lounge" (a lounge for several pilots)
• "the neighbors' fence" (a fence shared by the neighbors)
• "the employees' break room"
• "my grandparents' farmhouse"

When the plural form does not end in "s" — the irregular ones — treat it like a singular and add "'s":

• "the children's hospital"
• "the women's soccer team"
• "the people's verdict"
• "the oxen's yoke"

Shared vs. Separate Ownership

Two people who own something together share one apostrophe — on the last name only:

• "Priya and Marco's apartment" (they live in one place together)

If each person owns a separate version of the thing, every name gets its own "'s":

• "Priya's and Marco's laptops" (she has hers, he has his)

Hyphenated and Compound Owners

For compound nouns, the apostrophe hops to the very end of the whole unit:

• "my father-in-law's woodshop"
• "the editor in chief's memo"
• "nobody else's business"

Contractions and Shortened Words

A contraction squeezes two words together and uses the apostrophe as a placeholder for the letters that got squeezed out. Contractions are standard in speech and casual prose; many guides suggest spelling the words out in formal writing.

Common Contractions

Its vs. It's — The Big One

If a single apostrophe question is going to trip someone up, it is this one. The rules for possession and contraction seem to collide here, so it earns its own heading.

• It's = "it is" or "it has" — the apostrophe stands in for the vanished letter or letters.
• Its = belonging to it — no apostrophe, just like "his" or "hers."

Examples:

• "It's snowing again." (It is snowing.)
• "It's been a strange week." (It has been.)
• "The owl turned its head completely around." (The head belonging to it.)
• "The startup lost its biggest client." (The client belonging to the startup.)

The quick test: Say the sentence out loud with "it is" or "it has" in place of the word. If it still makes sense, write "it's." If it sounds broken, drop the apostrophe.

The reason "its" takes no apostrophe is the same reason "his," "hers," and "theirs" don't: possessive pronouns in English simply don't use one. If you would never write "her's" or "their's," don't write "it's" when you mean ownership. For a deeper dive, see the dedicated guide on its vs. it's.

The Apostrophe Is Not a Plural Maker

This is the most violated rule of them all: apostrophes do not create plurals. The infamous "greengrocer's apostrophe" — sticking one before the "s" of an ordinary plural — is wrong every single time.

• Wrong: "Ripe tomato's here" → Right: "Ripe tomatoes here"
• Wrong: "The Patel's just moved in" → Right: "The Patels just moved in"
• Wrong: "We have four dog's" → Right: "We have four dogs"
• Wrong: "USB's on sale" → Right: "USBs on sale"

One Narrow Exception

Several style guides allow an apostrophe with the plural of a lowercase letter, where the bare "s" would look like a typo:

• "Mind your p's and q's." (Without the mark, "ps" is hard to read.)
• "She came home with straight A's."

For uppercase letters and for numbers, leave the apostrophe out: write "the 1990s" rather than "1990's," and "two PhDs" rather than "PhD's."

Tricky Situations

Time and Measurement

Blocks of time can "own" something in English, so they take the possessive apostrophe:

• "a morning's work"
• "three weeks' vacation"
• "a decade's research"
• "five minutes' silence"

Idioms With "Sake"

A handful of fixed phrases use the apostrophe in quietly unusual ways: "for goodness' sake," "for appearance's sake," "for conscience' sake."

Whose vs. Who's

Same pattern as its/it's, with the same solution:

• Who's = "who is" or "who has"
• Whose = belonging to whom

You're vs. Your

The same confusion shows up here, and it gets its own walkthrough in the guide on your vs. you're:

• You're = "you are"
• Your = belonging to you

They're, Their, and There

Three homophones, one long-running mix-up, covered in the guide on there, their, and they're:

• They're = "they are"
• Their = belonging to them
• There = in that place

Mistakes That Keep Showing Up

1. Turning plurals into possessives: Writing "banana's" when you just mean more than one banana. Never.
2. Swapping its and it's: Using "it's" for ownership or "its" for "it is." The contraction test fixes this every time.
3. Putting the apostrophe on the wrong side of the s: "the boy's hats" (one boy) versus "the boys' hats" (multiple boys). Ask how many owners first, then place the mark.
4. Dropping the apostrophe in a contraction: "dont," "cant," or "isnt" instead of "don't," "can't," "isn't."
5. Decorating decades: "The 1980's were loud" is wrong when you simply mean the plural. Write "the 1980s." The apostrophe is only correct when letters are actually missing: "the '80s."
6. Apostrophes on possessive pronouns: "her's," "their's," "our's." These forms do not exist. The correct words are hers, theirs, ours, yours, and its.

Rules at a Glance

The apostrophe has a reputation as the most abused mark in English, but the whole system really does come down to two questions: am I showing that something belongs to someone, or am I signaling that letters have been left out? If neither answer is yes, you almost certainly don't need the apostrophe at all. Keep that in mind and you will sail past the bulk of mistakes that even experienced writers still make.