Commas (,)
The comma is one of the most versatile punctuation marks. It separates ideas, phrases, and clauses, helping to clarify meaning and make sentences easier to read.
What Is a Comma?
A comma (,) is a punctuation mark that indicates a pause in a sentence. It helps to separate ideas, clauses, or items in a list, making the sentence structure clearer and easier for the reader to understand. Proper comma usage is one of the most important aspects of clear writing.
When to Use a Comma
Commas have many important functions in a sentence.
| Usage | Description | Example |
|---|---|---|
| Separating Items in a List | To separate three or more words, phrases, or clauses in a series. | "I need to buy milk, eggs, and bread." |
| Separating Independent Clauses | To separate two independent clauses joined by a coordinating conjunction (for, and, nor, but, or, yet, so). | "She wanted to go to the beach, but it was raining." |
| After Introductory Elements | To separate an introductory word, phrase, or clause from the main clause. | "After the movie, we went for ice cream." |
| Setting Off Non-essential Elements | Commas are used to enclose information that is not critical to the main meaning of the sentence. This includes "non-restrictive" clauses, phrases, and appositives (phrases that rename a noun). A good test is to see if the sentence still makes complete sense after removing the part between the commas. If it does, the information is non-essential and needs commas. For example, in "My brother, who is a doctor, lives in New York," the main point is that my brother lives in New York. The fact that he is a doctor is extra information. However, in a sentence like "The student who finishes first will get a prize," the clause "who finishes first" is essential to identify which student gets the prize, so no commas are used. | "My brother, who is a doctor, lives in New York." |
| Separating Adjectives | To separate two or more coordinate adjectives that describe the same noun. | "It was a long, cold winter." |
| Direct Address | To set off the name of a person being directly addressed. | "John, could you please close the door?" |
| Dates, Addresses, and Numbers | To separate elements in dates, addresses, and large numbers. | "She was born on May 5, 2005, in Chicago, Illinois." |
| Introducing Quotations | To introduce a direct quotation. | "He said, "I will be there soon."" |
Pro Tip: The Oxford Comma
The comma before "and" in a list of three or more items (e.g., "red, white, and blue") is known as the Oxford or serial comma. While some style guides consider it optional, using it can prevent ambiguity and is often preferred in formal writing.
Key Takeaways
- Commas separate elements in a sentence to improve clarity.
- Use commas in lists, with conjunctions, after introductory elements, and to set off non-essential information.
- Correct comma usage is essential for clear and professional writing.
- When in doubt, read the sentence aloud; natural pauses often indicate where a comma should go.
Exercises and Worksheets
Ready to practice? Test your knowledge with these resources.