Use apostrophes to show possession, indicate plural letters, and form contractions

An apostrophe is a punctuation mark used to show possession, to indicate the plural form of letters of the alphabet, and to form a contraction.

Of all forms of punctuation, the apostrophe appears to be in greatest peril of extinction. For proof that the apostrophe should be placed on an endangered species list in some grammarian’s office, one needs only to consult the popular press or a sample of student themes. However, because of its ability to denote ownership in a concise way (by avoiding the use of a preposition), the apostrophe plays an important role in the English language. Despite the frequency of its misuse, the apostrophe is a fairly simple form of punctuation to master.

How should apostrophes be used?

Use an apostrophe to denote ownership to a singular or plural noun and indefinite pronoun by adding an -‘s if the word doesn’t end in -s.

  • Use an apostrophe and -s (-’s) to show possession of singular nouns.
    • the author’s main point
  • Use an apostrophe and -s (-’s) to show possession of indefinite pronouns.
    • someone’s books
  • Use an apostrophe and -s (-’s) to show possession of irregular plural nouns.
    • the women’s scarves

You can denote ownership to a singular or plural noun and indefinite pronoun by adding an -‘s if the word doesn’t end in -s:

  • They worked on Susan’s computer.
  • The children’s toys are clustering the house again.
  • You expect me to do a week’s worth of typing in two days.
  • The people’s choice was Bill Clinton.
  • When it is someone else’s turn to have his or her writing critiqued by the group, remember to be conscientious.

When a singular noun ends in -s, traditional grammarians recommend adding an -‘s:

  • She loves Keats’s poems.
  • The business’s direct-mailing campaign worked wonders.
  • John Adams’s letters illustrate his reflective spirit.

However, this usage can be cumbersome. Consequently, the following usage is also correct:

  • John Keats’ conscience and life spirit energize his poems.
  • John Adams’ ideas are worth examination.

When a plural noun ends in -s, you only need to add an apostrophe:

  • Use an -s followed by an apostrophe (-s’) to show possession of plural nouns.
    • the students’ final grades
  • The judge confiscated the drivers’ licenses.
  • She won two months’ free groceries.
  • The writers’ guild meets Monday.

With compound subjects, when you wish to denote individual ownership, you should add an -‘s to each noun:

  • Dr. Wilson’s and Mr. Speinberg’s lawsuits were caused by poor communication.

Or, you can demonstrate joint ownership by placing the -‘s after the second subject:

  • Pat and Joe’s new car is hot!
  • This is my father-in-law and mother-in-law’s office.
  • Use an apostrophe and -s (-’s) to form the plural of letters of the alphabet.
    • Watch your p’s and q’s.

Finally, always use an apostrophe when you form a contraction. The apostrophe is positioned where letters are dropped:

it isit’s
they arethey’re
you areyou’re
who iswho’s
can notcan’t
she willshe’ll
were notweren’t

Avoid misuse of apostrophes

  • Do not use an apostrophe in possessive pronouns.
    • Incorrect: That notebook is your’s, and those pens are their’s.
  • Do not use an apostrophe in plural nouns that are not possessive.
    • Incorrect: Please ask the instructor’s to make an announcement to their student’s.
  • Do not use an apostrophe in the word its unless it’s the contraction for it is.
    • Incorrect: The lost dog has a sad look on it’s face.

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