Apostrophe rules: possession and contractions

The apostrophe replaces the missing letters:

Contractions are fine in informal writing and dialogue, but formal essays usually use the full form.

One owner: add 's.

• the dog's lead (one dog)
• the teacher's desk (one teacher)

More than one owner, plural ending in s: add just the apostrophe.

• the dogs' leads (several dogs)
• the teachers' staffroom (many teachers)

Plurals that don't end in s: add 's.

• the children's books, the women's team, the people's choice

The trick: write the owner first (dog, dogs, children), then add the apostrophe. If the word already ends in an s because it's plural, just add the apostrophe.

Both James's book and James' book are accepted. Many style guides prefer James's, because it matches how most people say it. Pick one and be consistent. For famous or historical names, Jesus' and Achilles' heel are traditional.

This is the most common apostrophe mistake.

• It's always means it is or it has: It's raining. It's been a long day.
• Its means belonging to it: The cat licked its paw.

Test: replace the word with "it is". If the sentence still makes sense, use it's. Possessive pronouns never take an apostrophe: its, yours, hers, ours, theirs, whose.

• Plurals: "apples £1", not "apple's £1". "The 1990s", not "the 1990's". "CDs" and "MPs", not "CD's" and "MP's".
• Verbs: "she walks", not "she walk's".
• Possessive pronouns: "the book is yours", not "your's".

• Joint: Sam and Amy's house (one house they share). The apostrophe goes on the last name only.
• Separate: Sam's and Amy's phones (each has their own). Both names get an apostrophe.

Time phrases also take apostrophes: a week's holiday, two weeks' notice, tomorrow's lesson.

Correct the apostrophes:

1. The girls bags were on the floor. (several girls)
2. Its been a long day and the dog wants it's dinner.
3. The childrens toys were everywhere.
4. Potato's for sale.
5. Whos coat is this?

Answers: 1. The girls' bags. 2. It's been a long day and the dog wants its dinner. 3. The children's toys. 4. Potatoes for sale. 5. Whose coat is this?

In AQA GCSE English Language, the writing section of each paper is marked for content and organisation and, separately, for technical accuracy (AO6), which includes spelling and punctuation. Apostrophe errors are easy to spot and easy to fix, so check every its, it's and plural before you finish. See also our guides to comma rules and semicolons and colons.