Overview

The apostrophe is a small punctuation mark used in many writing systems to indicate omitted letters, possession, or other linguistic features. It is sometimes described as a punctuation mark and at times functions like a diacritic when it alters pronunciation or morphology. Writers and typographers treat it differently from related marks such as quotation marks or the prime sign.

Primary uses in English

In modern English the apostrophe has two main roles: showing omitted letters in contractions and marking possession. Examples include don't for do not and Emma's book for the book that belongs to Emma. It is not used to form the regular plural of most nouns (for example, apples, not apple's).

Other functions and examples

  • Indicating omitted letters in other languages (elision), as in certain Romance languages.
  • Separating letters, numbers, or words for clarity: sometimes used in plurals of single letters (dot the i's) or in decades written informally (the 1980's is often discouraged).
  • Serving as a marker in transliteration to show glottal stops or other sounds in some languages.

History and typographic forms

The mark developed in European typography to indicate omitted letters and gradually entered many modern orthographies. Typographically it appears as a straight apostrophe on many keyboards (') or as a curved typographic apostrophe (’). Style guides disagree about which form to use; desktop publishing and fonts often supply the curly variant automatically.

Common pitfalls and style notes

Frequent errors include confusing its (possessive) and it's (contraction of it is or it has), using apostrophes for regular plurals, and inconsistent placement with plural possessives (the girls' room vs the girl's room). Different editorial manuals set rules for names ending in s, dates, and joint possessives.

Further reading

For introductions to punctuation and typographic conventions see general guides to punctuation and discussions of diacritical marks such as the apostrophe-like characters in other alphabets at diacritic resources.