Setting Off Nonrestrictive Elements with Commas, Parentheses & Dashes

People haven't always agreed on how to use commas, parentheses, and dashes. For centuries, writers and scholars experimented with different marks to show readers which parts of a sentence are "extra" information. Here's a quick look at how these punctuation tools developed over time.

So here's the big question this lesson answers: What is a nonrestrictive element, and how do you choose between commas, parentheses, and dashes to set it off?

Before you can use the punctuation, you need to understand two key ideas: restrictive elements and nonrestrictive elements. Don't worry — they're simpler than they sound!

Let's look at a quick example. Notice the difference:

Here, "who won the science fair" tells us which student. Without it, we wouldn't know who gets the trophy. It restricts (narrows down) the meaning, so no commas.

Here, we already know it's Maria. The phrase "who won the science fair" is just bonus info about her. Remove it and the sentence still works: "Maria will get a trophy." That's why it gets commas.

The diagram below shows you how a sentence is built when it has a nonrestrictive element. The main sentence (the essential part) is in blue. The nonrestrictive bonus information is in pink, and the punctuation marks that set it off are in gold.

As you can see, the pink dashed box (the nonrestrictive element) can be lifted right out of the sentence. The blue parts snap together and the sentence still works perfectly. The gold commas are what mark the boundaries so the reader knows that section is bonus information.

You have three different tools you can use to set off nonrestrictive elements. Each one does the same basic job, but with a slightly different "personality." Let's look at each one.

Commas are your everyday workhorse. When you set off nonrestrictive information with commas, the sentence reads smoothly. The reader barely pauses. This is the most common style and the one you'll use most often in school writing. Remember, you need two commas — one before the bonus information and one after — unless the nonrestrictive element comes at the very end of the sentence (then one comma is enough).

Parentheses are for information that feels like a quiet side note. Imagine you're telling someone a story and you lean in to whisper a small detail before continuing. That's the vibe of parentheses. They signal to the reader: "This is helpful but not super important." Use them for facts, dates, abbreviations, or little clarifications.

Dashes (em dashes) are the dramatic option. When you use dashes, you're saying: "Hey, notice this cool detail!" Dashes create a bigger pause than commas, so the extra information really stands out. They work great when the bonus info is surprising, funny, or especially important. Use the long dash (called an em dash: —), not a short hyphen (-).

Now that you know the three punctuation tools, let's explore when each one works best. The diagram below maps out common situations and which tool to reach for.

Here's something important to remember: all three tools are grammatically correct. Your choice depends on the tone you want. In a school essay, commas are usually the safest bet. In creative writing, dashes can add flair. In a research report, parentheses work well for dates and technical details.

Let's walk through a complete example step by step. Imagine you're writing a paragraph about your school, and you have this sentence to improve:

Each punctuation tool has strengths and weaknesses. Let's look at what works well and what to watch out for.

One of the biggest mistakes students make is confusing restrictive and nonrestrictive elements. Here's a tricky pair to practice with:

This means only the students who study regularly earn better grades — not all students. The phrase is essential to the meaning.

This means ALL sixth graders study regularly (and they all earn better grades). The phrase is just describing them, not narrowing down which ones.

The skill you're learning right now doesn't just help you in 6th grade — it's a tool you'll keep using through high school, college, and beyond. Let's see how this concept grows with you.

In more advanced writing, you'll also learn about semicolons, colons, and how to combine multiple types of punctuation in the same sentence. For now, mastering commas, parentheses, and dashes gives you a solid foundation. You're building the skills that make great writers great!

One tip as you move forward: pay attention to punctuation when you read books, articles, or even social media posts. You'll start noticing nonrestrictive elements everywhere. Seeing how other writers use them will help you use them more naturally in your own writing.

Time to test what you've learned! Try each problem on your own, then click "Show Answer" to check your thinking.