Apostrophes do only two jobs in English: they show possession and they mark missing letters. Almost every apostrophe mistake comes from using one for a third job: making plurals.

Job 1: Possession #

Singular noun: add 's.

  • the dog's bowl (one dog)
  • my boss's email
  • James's car (James' is also accepted)

Plural noun ending in s: add only '.

  • the dogs' bowls (more than one dog)
  • the students' grades

Plural noun not ending in s: add 's.

  • the children's toys
  • the women's team

Job 2: Contractions #

The apostrophe replaces missing letters.

  • don't = do not
  • it's = it is / it has
  • you're = you are
  • '90s = 1990s

Never use an apostrophe for plurals #

This is the most common apostrophe mistake.

Wrong Right
apple's for sale apples for sale
two iPhone's two iPhones
the 1990's the 1990s

Possessive pronouns have no apostrophe #

His, hers, its, ours, yours, theirs, and whose never take an apostrophe.

  • The app updated its icon. (not it's)
  • Is this yours? (not your's)

See also: its vs. it's and whose vs. who's.

A quick checklist #

  1. Is it a contraction? → apostrophe where letters are missing.
  2. Does something belong to someone? → 's (singular) or s' (plural ending in s).
  3. Is it just more than one? → no apostrophe.

Let AI place them #

AI Grammar Checker fixes misplaced and missing apostrophes along with the rest of your punctuation.