Apostrophes are used with nouns and indefinite pronouns to show ownership; to indicate the omission of letters and figures in contractions; and to form the plural of letters, figures, and words that are referred to as words.

  1. Ownership is indicated by the apostrophe when something belongs to, is owned, or is possessed by someone or something else. Possession can also be indicated by time (e.g. a month's vacation or a week's pay).Use an apostrophe and s ('s) to form the possessive of a noun, singular or plural, that does not end in s (e.g. a man's coat or men's coats).
  2. Use either an apostrophe and s ('s) or the apostrophe alone (') to form the possessive of singular nouns ending in s.  Use the apostrophe and s ('s) only when you would pronounce the s. (e.g. James' hat or James's hat)
  3. Plural nouns that end in s form the possessive by adding just an apostrophe (e.g. the ladies' room or five students' book bags) Note: Do not confuse plural noun that ends in s with a possessive noun showing ownership.  Example: The ladies meet for lunch at the Lobster House. The ladies' luncheon will be held at the Lobster House.
  4. Use an apostrophe and s to indicate that an indefinite pronoun is possessive (e.g. everybody's ideas).  Note: Apostrophes are not used to form the possessive of personal pronouns (e.g. his book, her sweater, its tail).
  5. Use an apostrophe to indicate that letters or figures have been omitted (e.g. o'clock, meaning of the clock, or '90s, meaning 1990s).
  6. A contraction is a combination of two or more words. The apostrophe in a contraction indicates where letters have been omitted (e.g. you're = you are and we'll = we will).
  7. Use an apostrophe to indicate the plural when letters or figures are used as words (e.g. crossing you t's and dot your i's).

Additional Examples

Try to avoid making these kinds of errors when using contractions and/or personal pronouns:

Example 1

Incorrect: The dog bit it's tail. (it's is the contraction of it is)
Correct: The dog bit its tail. (its is a possessive personal pronoun)

Example 2

Incorrect: Whose the leader now? (Whose is a possessive personal pronoun)
Correct: Who's the leader now? (Who's is the contraction of who is)