The apostrophe is used to show possession and to form the plural of many nouns and symbols, as well as to indicate the omission of letters in contractions.

Possessive of Singular Nouns

The possessive of a singular noun is formed by adding ’s. Names that end in a z sound often take only the apostrophe to avoid the awkwardness of too many s sounds.

• • the mechanic’s wrench
  • the tree’s leaves Moses’ tablets
  • Mrs. Gonzales’s maid
  • Gloria’s backpack
  • Mr. Jones’ iPod
  • Carlos’s notebook
  • Ned Stanis’s boots

Possessive of Plural Nouns

The possessive of plural nouns ending in s is formed by adding only the apostrophe. All other plural nouns take ’s.

• • the Harlands’ trip
  • children’s shoes
  • the teams’ scores
  • the trees’ leaves
  • men’s sportswear
  • women’s networks

Possessive of Indefinite and Personal Pronouns

Indefinite pronouns (everyone, no one, anybody, everybody, someone, somebody, one) require an apostrophe to form the possessive. However, personal possessive pronouns (his, hers, theirs, your/yours, my/mine, our/ours) do not use an apostrophe.

• • Is this someone’s book?
  • Yes, the book is hers.
  • I’ll take anyone’s ideas.
  • Your ideas are great.

Individual and Joint Possession

To show joint possession by two or more organizations, companies, or individuals, only the last word takes ’s or an apostrophe. In cases of individual possession, both nouns and pronouns take ’s or the apostrophe only.

Joint possession:

• • Lin and Chan’s bicycle (The bicycle is owned by both Lin and Chan.)
  • The vice presidents’ office (The office is used by more than one vice president.)
  • IBM and Xerox’s new venture (The two companies are working together on one venture.)

Individual possession:

• • Lin’s and Chan’s bicycles (Notice the plural noun after the names—a clue that each person owns a bicycle.)
  • her father-in-law’s and brother’s golf scores
  • Texaco’s and BP’s annual reports

Units of Measure as Possessive Adjectives

Units of measure such as day, week, yard, cent, and hour take ’s or an apostrophe when used as possessive adjectives.

• • a moment’s peace
  • a month’s pay
  • a dollar’s worth
  • ten minutes’ work
  • three weeks’ pay
  • two cents’ worth

Plural Forms of Symbols

The apostrophe or ’s is used to form the plural of letters, numbers, signs, symbols, and words referred to as words.

• • All the R’s in this article were printed backward.
  • Mark these items with X’s and those with O’s.
  • Your 3’s look like 8’s.
  • How many and’s can you put in one sentence?
  • The printer smudged all the g’s in my report.
  • We can use +’s and *’s in the chart.

Contractions

The apostrophe is also used to indicate letters that have been omitted to form contractions of verbs. Contractions are used in informal writing and conversation, but are generally avoided in formal writing.

• • She will come tomorrow.
  • She’ll come tomorrow. (wi in will omitted)
  • I have not heard from him.
  • I’ve not heard from him. (ha in have omitted)

Formal writing: Do not send the second shipment by UPS.

Informal writing: Don’t send the second shipment by UPS. (o in not omitted)