An apostrophe is a punctuation mark (') used to indicate possession or omission.

Possession
Possession of singular nouns
To show possession of a single noun, the apostrophe + s is added to the following: 

 

Examples:

  • This morning, my grandmother appeared more cheerful than my grandfather.
  • noun that end in –s: actress's role; princess's lover; rhinoceros's skin
  • noun or name: uncle's pipe; George's girlfriend; dog's tail; Thomas's car
  • person's office or shop: I'll buy the pork at the butcher's. / I'll be visiting Tom's.
  • only after the second name to show joint ownership: Jack and Jill's pail; Bonnie and Clyde's loot
  • both names to indicate separate ownership: Jack’s and Jill’s cars  

 

Possession of plural nouns
To show possession of a plural noun, the apostrophe + s is added to the following:

 

Examples:

  • plural nouns that end in –s: boys' bicycles; friends' houses; books' covers
  • plural nouns that do not end in –s: children's toys; women's clothes; men's boots
  • plural of abbreviations: many Dr.'s; many M.D.'s; many Ph.D.'s.
  • plural of a letter: Your p's, and c's are too big. / You must dot your i's and cross your t's.
  • plural of word or phrase: There are too many I’s and you know’s in his speech.

 

Omission
An apostrophe + s is used to show letters or numbers that have been left out.

Omission of letters

Examples:

  • Using apostrophe to contract words: I'm = I am; we’re = we are; don’t = do not; can’t = cannot: rock ’n’ roll = rock and roll
  • Using ‘s for is and has: he’s = he is/he has; it’s = it is/it has 
  • Using ’d for had and would: they’d = they had/they would; she’d = she had/she would 

 

In short answers, we can omit the noun if it is not necessary to repeat it:

Examples:

  • Is that your coat?
  • No, it’s Sandra’s.

 

Omission of numbers

Examples:

To show plural of a number: 

  • Your 5's are too big. 

To show that a number has been left out: 

  • My grandfather died in '86.
  • My grandfather died in 1986.

To show the plural of a number that has been left out:

  • The uprising happened in the '60's. 
  • The uprising happened in the 1960's.

 

Apostrophe + s used with singular noun

Examples:

  • To show time: The workers took an hour’s break for lunch.
  • To show time: The library is just fifteen minutes’ walk from my house.
  • To show day: Why do you give me yesterday’s newspaper when I asked for today’s?
  • To show week: We will be making a week’s trip to the uninhabited island.
  • To have double apostrophes: We were at James’ (or James’s) father’s office when he called.

 

Apostrophe + s used with compound noun

Examples:

  • No: My mother's-in-law waistline is expanding fast.
  • Yes: My mother-in-law's waistline is expanding fast.

 

When apostrophe + s is not used to show possession
So far the noun or nouns to which the apostrophe + s is added to show possession has/have been living things. For non-living things, the apostrophe + s is not used. Instead, of the is used to show something is part of a non-living thing. The reason for this is that unlike living things, non-living things cannot own things.

 

Examples:

  • No: Your car's windscreen wipers need to be replaced.
  • Yes: The windscreen wipers of your car need to be replaced.
  • No: The air was black from the factory's smoking chimneys.
  • Yes: The air was black from the smoking chimneys of the factory.
  • No: Look, the shovel's handle must be held like this.
  • Yes: Look, the handle of the shovel must be held like this.