Apostrophe Rules | Apostrophe Definition and Apostrophe Examples

What Is an Apostrophe?

An apostrophe is a type of punctuation mark that helps indicate possession, the omission of certain letters or numbers, and some plural forms. Learning the apostrophe rules can be the most important component of learning about the apostrophe.

Possessive of a Singular Noun

To form the possessive of a singular noun, add an apostrophe and an s to the word.

Singular Noun Apostrophe Rules Examples:

Apostrophe Rules Example 1:

I have to drop off the food at my mother’s house.

Apostrophe Rules Example 2:

When he hit the ball, the player ’s bat split in half.

Apostrophe Rules Example 3:

Zoe admired her friend ’s flower garden.

Apostrophe Rules Example 4:

The sun ‘s heat quickly warmed up the swimming pool.

Apostrophe Rules Example 5:

David ’s bike needs to have its tires inflated.

Possessive of a Plural Noun Ending in s or es

To form the possessive of a plural noun ending in s or es, add an apostrophe after the final s in the word.

Plural Noun Apostrophe Rules Examples:

Apostrophe Rules Example 1:

Both of the two hostesses’ dinner parties were a great success.

Apostrophe Rules Example 2:

Julian borrowed his parents’ car to drive to school.

Apostrophe Rules Example 3:

The musicians’ sheet music blew away during the outdoor concert.

Apostrophe Rules Example 4:

Our puppies’ food bowls need to be filled.

Apostrophe Rules Example 5:

The cherries’ pits should be removed before we make the pie.

Possessive of a Plural Noun Not Ending in s or es

To form the possessive of a plural noun that does not end in s or es, add an apostrophe and an s to the word.

Apostrophe Rules Examples:

Apostrophe Rules Example 1:

Could you pick up the children’s toys?

Apostrophe Rules Example 2:

The mice’s nests are full of babies.

Apostrophe Rules Example 3:

Some people’s vacations are relaxing, but hers are usually adventurous.

Apostrophe Rules Example 4:

The women’s volleyball team is playing tomorrow night.

Apostrophe Rules Example 5:

We saw three moose’s tracks on the trail.

Possessive of Pronouns

To form the possessive of an indefinite pronoun, add an apostrophe and an s to the word.

Apostrophe Rules Examples:

Apostrophe Rules Example 1:

I try to remember everyone’s birthday.

Apostrophe Rules Example 2:

Brandon found someone’s backpack in the library.

Apostrophe Rules Example 3:

Anybody’s friends are welcome to join us at the party.

Apostrophe Rules Example 4:

The fact that we were late wasn’t anyone’s fault.

Apostrophe Rules Example 5:

No one’s car would start after the temperature dropped to -20°F.

Do not add an apostrophe to plural possessive pronouns.

Apostrophe Rules (When not to use an apostrophe):

The blue Toyota is theirs.

The homework on the table is hers.

The house’s spacious, open design is its best quality.

Omissions in Contractions

Place an apostrophe where letters are omitted in contractions.

Apostrophe Rules Examples:

Apostrophe Rules Example 1:

I’m going to take a nap.

Apostrophe Rules Example 2:

Daisy can’t make it to the game today.

Apostrophe Rules Example 3:

Eve and Nick said they’re going to help us move.

Apostrophe Rules Example 4:

It’s going to rain today.

Apostrophe Rules Example 5:

They’ll call you tomorrow to schedule an appointment.

In Dates

Place an apostrophe where numbers are omitted in dates, but do not place an apostrophe before the s in the plurals of dates.

Apostrophe Rules for Dates Examples:

Apostrophe Rules Example 1:

I graduated in ’08.

Apostrophe Rules Example 2:

In ’04, we moved into our new house.

Apostrophe Rules Example 3:

Fashion was very different in the ’80s than it is now.

Apostrophe Rules Example 4:

In the ’30s, the country was in the midst of the Great Depression.

Apostrophe Rules Example 5:

The tech industry had a major effect on the economy in the 1990s.

Plural Forms

Add an apostrophe and an s after the plural forms of lower-case. Add an s, but not an apostrophe, to the plural forms of upper-case letters.

Apostrophe Rules for Plural Forms Examples:

Apostrophe Rules Example 1:

Mississippi has four s‘s and four i‘s.

Apostrophe Rules Example 2:

Phillip spells his name with two l’s instead of one.

Apostrophe Rules Example 3:

Be sure to dot your i’s and cross your t‘s.

Apostrophe Rules Example 4:

Gabriel just learned his ABC s.

Apostrophe Rules Example 5:

My financial advisor suggested that I look into IRA s.

Check out our free, printable Apostrophe Worksheets!