Apostrophes can be used in three ways: to form contractions, to create plurals, and to show possession.* Read up on the details below and then take our quiz!
Apostrophes are used to form contractions—that is, words that are shortened by omitting one or more letters—for example, you’re for you are, ma’am for madam, tellin’ for telling, and ’til for until.
When the apostrophe is at the start of the word—as in ’til—be sure that the punctuation mark is inserted correctly. It should look like a single closing quotation mark, not an opening one.
Apostrophes are used to form the plurals of letters:
Accommodation has two c’s and two m’s.
Mind your p’s and q’s.
She had three scarlet A’s on her back.
But apostrophes are not used for the plurals of letters referring to grades or for the plurals of abbreviations containing capital letters:
She got three As.
This program is open to people with MAs and PhDs.
Apostrophes are used to show possession. For singular nouns and irregular plurals (those not ending in s), you should add ’s to the end of the word. For plural nouns ending in s, you should add only an apostrophe:
the cat’s meow
the people’s choice
an old wives’ tale
Note, though, that when a word ending in s is the same in the plural as it is in the singular, you just add an apostrophe:
identity politics’ critics
Also add only an apostrophe for proper names when the name is plural but the entity is singular:
the United States’ policy on China
In MLA style, proper nouns ending in s that are singular follow the general rule and add ’s :
Alexandre Dumas’s novels
Some styles may allow you to add only an apostrophe: Athens’ history, Diogenes’ philosophy, Dumas’ novels.
If two nouns jointly possess something, use only one apostrophe:
My mom and dad’s house
But if each noun possesses something separately, use an apostrophe with each noun:
Smith’s and Johnson’s studies
Remember to use an apostrophe in phrases such as the following:
one week’s vacation (one week of vacation)
And use an apostrophe for the double possessive:
He is a friend of Steve’s (Steve’s is the equivalent of the possessive pronoun his: a friend of his.)
Though practices vary, you may omit the apostrophe when a noun modifies another noun—that is, when the first noun is attributive:
a teachers union (a union for teachers)
*These rules are adapted from the MLA Handbook, 7th edition.