Purpose of the Apostrophe

Apostrophes mark two things in writing: possession — whether the written noun has ownership over the following noun — and omitted letters in contractions, where two words are combined to make one.

Marking Possession with Apostrophes

Possession indicates that the noun being modified has some form of ownership or relationship with the noun that follows it.

  • Example: Amina’s jacket: the jacket that belongs to Amina
Singular Possessive

The possessive is formed in singular nouns by adding “-’s” to the end of the word, regardless of whether it ends in an “s” or not.

 Examples: The Little Pub’s sign; Matías’s basketball

Plural Possessive

The possessive is formed in plural nouns by adding “-’s” to the end of words that do not end in “s” and an apostrophe to the end of words that do end in “s.” 

  • Examples: The children’s toys; The students’ books

The apostrophe, or the “-’s” ending, never indicates that the word is plural. The word will always be marked as plural before a possessive ending is added.

Possessive Pronouns

Possessive pronouns, such as yours, hers, its, and ours, take no apostrophe.

  • Example: The decision is yours.
Indefinite Pronouns

Indefinite pronouns, such as anyone, everybody, no one, and somebody, refer to nonspecific persons and use the singular possessive form.

  • Example: Somebody’s dog was in our classroom yesterday.

Using Apostrophes in Contractions

Contractions appear frequently in speech, but in writing they require modifications to spelling to mimic their pronunciation. Consonant sounds are often omitted to make it easier to pronounce a contraction as one word; they are replaced in writing with an apostrophe to mark the missing letter. Contractions are sometimes considered too informal to use in academic writing, and you may want to write out the words forming the contraction separately instead.

  • Examples: do not = don’t; can not = can’t; should not = shouldn’t; will not = won’t
It’s vs. Its: It’s tricky!

It’s: This is the contraction of “it is” or "it has" and is never used to mark the possessive. 

Its: This is the possessive of “it” and, unlike other possessives, does not use an apostrophe.

  • Example: I got a new car, but it’s hard to tell whether its paint is blue or green.

By Laura Widman, Writing Center Assistant Director

See Sin No. 5

Student on computer

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