Showing Possession ('s vs. of)

Basic · Nouns & Articles

To show that something belongs to someone, English mainly uses an apostrophe + s ('s). For people and animals this is the natural choice: "Sara's book", "the dog's tail".

For objects and ideas, we often prefer "of": "the roof of the house". Getting the apostrophe in the right place is the tricky part.

How to build it

singular + 's · plural ending in -s → add only ' · the ___ of the ___

Rules & examples

1. Add 's to a singular noun.

   This works even if the word already ends in -s (both forms are accepted).

   • the girl's book
   • James's car (or James' car)
2. For a plural noun already ending in -s, add just an apostrophe.

   Do not add another s.

   • the students' teacher
   • the dogs' owner
3. For irregular plurals (no -s), add 's.

   Because they do not already end in s.

   • the children's toys
   • the people's choice
4. Use "of" for things and ideas rather than people.

   It sounds more natural for objects.

   • the roof of the house
   • the end of the film
5. Use 's for time expressions.

   Time acts like an "owner" here.

   • today's news
   • a week's holiday
   • two hours' drive

Tips to remember

• Position tells you the number: dog's = one dog; dogs' = many dogs.
• Never use an apostrophe just to make a plural: it is 'apples', not 'apple\'s'.

Common mistakes

• ✗ the book of the girl → ✓ the girl's book — For people, 's sounds far more natural than 'of'.
• ✗ the childrens' room → ✓ the children's room — "Children" is already plural, so add 's (not s').