Apostrophes: When to Use Apostrophes in Writing (Examples)

This article is for you if you want to learn more about apostrophes and how to use them. You'll learn the rules around proper usage and avoiding the most common mistakes.

In short:

Apostrophes are symbols used with specific words to show possession, contractions, or omissions. 

This guide is part of our free online Grammar Book.

When to Use Apostrophes

Before we get into exactly how to use an apostrophe, let's first determine what it is. Though it's often included in the punctuation category, they are actually different from most punctuation marks, which often have the purpose of separating structural units. Take the comma, for example. It separates two clauses and shows you should take a pause between them.

Apostrophes don't do that. But they do clarify certain words and affect the meaning, so they have at least that in common with other punctuation. Let's take a look at the proper usage of apostrophes.

Contractions and Omissions

An apostrophe's first job is to stand in for omitted letters. That means you can literally leave some letters out and use an apostrophe instead.

Look at the following sentence, for example:

The kids are having a great time; they're playing in the park.

• Notice the apostrophe in the word 'they're.' You could also say 'they are,' but that's longer because it's two syllables instead of one. So we use apostrophes to shorten our sentences.

Here are some examples:

Excuse me, ma'am, is this your suitcase?

Are you sure you're ok?

It's all good, we're having a great time!

This also works for slang words like y'all, doin', and ain't.

• You can also sometimes omit parts of a word in favor of an apostrophe. This is very common when writing years and decades.

Here's how that might look in practice:

1950s →'50s

class of 2008 →class of '08

Top Tip! Contractions are best kept for casual settings. In a formal setting, you should use the full, non-contracted words.

Form Possessive Nouns

The second biggest purpose of an apostrophe is to form a possessive noun. What's that? It's a noun that owns something. You can take any noun and make it possessive to talk about something that belongs to it. And in order to do that, you add an apostrophe and the letter 's.'

Let's take a look at some examples:

That man's accent is very strong. I can barely understand what he's saying.

I'm off to the beach! Who's coming with me?

Maria's mom called earlier.

As you can see, it works with proper and common nouns. It does not work, however, with possessive pronouns.

For example:

• You don't say her's; you say hers.

Common Errors with Apostrophes

Hopefully, you'll agree that apostrophe usage rules are pretty straightforward. And yet, there are some common errors that people often make. So what are they, and why do they make them? And more importantly, how can they be avoided? Let's find out.

Confusing the Possessive and Plural Forms

A noun can be both possessive and plural, making it confusing to know how to use apostrophes with them. A plural noun is more than one thing, person, or animal. A possessive shows ownership.

• The difference is that you use an apostrophe with possessives but never plurals.

Here are some phrases where the apostrophe is commonly misused:

Do's and don't's ❌
Dos and don'ts ✅

Born in the 90's ❌
Born in the 90s ✅

My collection of CD's ❌
My collection of CDs ✅

As you can see, the overall problem is that an apostrophe is often used to make a noun plural. Never use an apostrophe to make a noun plural. Only use an apostrophe to make a noun possessive. 

So ask yourself: does the noun you used refer to something's owner, or does it refer to more than one thing? If it's the former, use an apostrophe. If it's the latter, don't.

Look at the following sentences:

There are three boys in the sandpit.

They are playing in the boy's sandpit.

The first example describes three boys, so that's a plural, which means no apostrophe. The second sentence describes the sandpit as belonging to the boy, so that's possessive, which means you should use an apostrophe.

Let's take a look at another example:

My brothers are older than me.

My brother's bedroom is next to mine.

My brother's eleven years old.

The first sentence contains the plural noun brothers (so no apostrophe), and the second sentence contains the possessive noun brother's (so use an apostrophe).

And this time, I complicated things by adding in the contraction apostrophe. That's in the third sentence; did you spot it? My brother's stands for My brother is here.

Using Plural Possessives

What about plural possessives? Well, it's a combination of a plural and a possessive, so you'll use the plural s and the possessive s. For example, in the earlier sentence, " My brother's bedroom is next to mine, " implying that only one brother lives in that room.

Look at the following sentence, where two or more brothers live in the room next door:

My brothers' bedroom is next to mine.

Here are a few more examples:

Why are toucans' beaks so huge?

She won the Writers' Guild Award this year.

I don't envy teachers' jobs; it's a tough gig!

Possessive Pronouns and Adjectives

Another area that often trips people up is possessive pronouns and adjectives. Since apostrophes are used to form possessives, it would make sense to use an apostrophe for a possessive pronoun or adjective, right?

I wish it were that simple, but the truth is that while you do use an apostrophe to form a possessive noun, you don't use one to form a possessive pronoun or adjective.

Here are some examples of common errors:

The dog chewed on it's bone for hours. ❌
The dog chewed on its bone for hours. ✅

The rest of the night was their's. ❌
The rest of the night was theirs. ✅

The job is your's if you want it. ❌
The job is yours if you want it. ✅

I'm going to list below all the possessive pronouns and adjectives. As you'll see, none of them contain apostrophes, and that's the way it should stay!

Let's start with the possessive pronouns:

• my
• his
• her
• its
• our
• your
• their

And here are the possessive adjectives:

• mine
• his
• hers
• ours
• yours
• theirs

Concluding Thoughts on Apostrophes

And that concludes this article on the various uses of the apostrophe and how to avoid the most common mistakes.

Let's summarize what we've learned:

• Apostrophes are a form of punctuation, although they are a little different from most punctuation marks.
• You can use them to form contractions or possessive nouns.
• Never use them to form plural nouns.
• Don't use them with possessive pronouns and adjectives.

If you found this article helpful, you might like our Grammar Book, a free online database of grammar articles similar to this one. Check it out!