Commas and Semicolons | Open Textbooks

📖 Learn

Punctuation marks are like traffic signals for readers. They tell us when to pause, stop, or connect ideas. Let's master two important punctuation marks: commas and semicolons.

,

Comma

A short pause

;

Semicolon

A stronger pause

Comma Rules

1 Lists (Series)

Use commas to separate three or more items in a list.

I need pencils, paper, and an eraser.

2 Introductory Words

Use a comma after introductory words, phrases, or dependent clauses.

However, I decided to stay home.
When the rain stopped, we went outside.

3 Compound Sentences

Use a comma before coordinating conjunctions (and, but, or, so, yet) that join two independent clauses.

I wanted to play, but it was raining.

4 Extra Information

Use commas around non-essential information that could be removed.

My dog, a golden retriever, loves to swim.

Semicolon Rules

1 Joining Related Sentences

Use a semicolon to join two closely related independent clauses without a conjunction.

I love reading; my brother prefers video games.

2 Before Transitional Words

Use a semicolon before words like "however," "therefore," "moreover" when they connect two sentences.

She studied hard; however, she still felt nervous.

💡 The Big Difference

Comma: A small pause. Usually needs a conjunction (and, but, or) to connect independent clauses.

Semicolon: A bigger pause. Can connect independent clauses by itself, without a conjunction.

💡 Examples

Let's compare when to use commas versus semicolons.

Connecting Two Independent Clauses

With Comma + Conjunction

"The test was hard, but I did my best."

With Semicolon (No Conjunction)

"The test was hard; I did my best."

With Comma + Conjunction

"It rained all day, so we stayed inside."

With Semicolon + Transitional Word

"It rained all day; therefore, we stayed inside."

⚠️ Common Mistake: The Comma Splice

A comma splice happens when you use just a comma to connect two independent clauses without a conjunction. This is incorrect!

Wrong: I love pizza, my sister prefers tacos.
Right: I love pizza, and my sister prefers tacos.
Right: I love pizza; my sister prefers tacos.

More Examples

Lists

We visited Paris, London, and Rome.

Note: The last comma before "and" is called the Oxford comma. It's optional but helps prevent confusion!

After Introductory Elements

Yes: After the movie, we got ice cream.
Yes: Suddenly, the lights went out.
Yes: Although she was tired, she finished the race.

Semicolons with Transitional Words

He practiced every day; consequently, he made the team.

Notice: Use a semicolon before the transitional word and a comma after it.

✏️ Practice

Fill in the Punctuation

Choose the correct punctuation for each sentence.

🎯 Punctuation Challenge

Score: 0 Question: 1/8

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Fix the Punctuation

The sentence below has incorrect punctuation. Type the corrected version.

Correct this sentence:

"I wanted to go to the park, it was raining outside."

✅ Check Your Understanding

Question 1

Which sentence uses the comma correctly?

Question 2

What punctuation should go in the blank? "She finished her homework ___ then she watched TV."

Question 3

What is a "comma splice"?

Question 4

Which sentence correctly uses a semicolon?

Question 5

Which of these needs a comma after the first word/phrase?

🚀 Summary & Next Steps

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Comma Uses

Lists, introductions, compound sentences

;

Semicolon Uses

Join related sentences, before transitional words

⚠️

Avoid Comma Splices

Don't join sentences with just a comma

✨

Practice

Read aloud to hear natural pauses

💡 Writing Tips

Read your writing aloud—pause briefly at commas and longer at semicolons.
When in doubt between a comma and semicolon, ask: "Can both parts stand alone as sentences?"
Use semicolons sparingly—they're powerful but can make writing feel formal.
Check for comma splices by looking at each comma and asking if you need "and," "but," or "or."

Continue Learning

Review the previous lesson on Independent and Dependent Clauses
Practice identifying commas and semicolons in books and articles
Edit your own writing with these rules in mind