Apostrophe Punctuation
Apostrophe decisions are easiest when you first identify the job: possession, contraction, or plural formation. Possession and contractions commonly need an apostrophe, while ordinary plural nouns do not. House styles can differ on narrow edge cases.
Use apostrophes mainly to mark possession and omitted letters in contractions. Ordinary plurals normally take no apostrophe; special cases such as names ending in s and some letter or symbol plurals can depend on the governing style guide.
Key details
Important caveats
Boundary
Check the required style for possessives of names ending in s and for unusual letter/symbol plural conventions.
Further guidance
Decision Path
If the form shows ownership or association, apply the possessive pattern required for that noun. If letters are omitted in a contraction, place the apostrophe where the omission occurs.
Plural Test
If you are merely making an ordinary noun plural, do not add an apostrophe.
Worked Example
“The editor’s note” is possessive; “editors” is a plural; “don’t” marks omitted letters in “do not.” The three forms use different tests.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- The Apostrophe (opens in a new tab)Purdue Online Writing Lab · Purdue distinguishes apostrophe uses for possessives, omitted letters in contractions, and certain letter plurals, while warning against apostrophes in ordinary plurals and possessive pronouns.
- Apostrophes (opens in a new tab)Australian Government Style Manual · The Style Manual gives detailed possession, contraction, plural, descriptive-phrase, shortened-form, and style-boundary rules for apostrophes.