Commas matter. They can change the meaning of an entire sentence and they allow the reader to understand the proper connotation of what a writer is attempting to convey. That’s a lot of heavy lifting for this punctuation period with a tail.
Commas serve a specific purpose; they exist to separate clauses, introduce or identify dialogue, to delineate a list of items from one another, are used before conjunctions, to offset “interruptive” wording and to indicate sentence continuation before and after quotation marks.
Commas are one of the most complex and most misunderstood in proper punctuation usage. When and how to utilize commas (and when not to use them) is actually pretty straightforward if you can remember a handful of comma “rules”.
1. A sentence listing two items, subjects or verbs never requires a comma. A list of three or more items, subjects or verbs does require a comma.
Examples:
- I went to the grocery store for milk and eggs. (No comma required)
- I went to the grocery store for milk, eggs, and bread. (Comma required)
- Anne and Jamie went to the beach. (No comma required)
- Anne, Jamie, and Cindy went to the beach. (Comma required)
- My dog barked and ran. (No comma required)
- My dog barked, ran, and wagged his tail (Comma required)
2. Conjunctions are those tiny words that join other words or sentences or clauses together. Use a comma before, not after a conjunction.
Examples
- She took a nap, and then made a sandwich. (Comma before the conjunction “and” is correct)
- She took a nap and, then made a sandwich. (Comma after the conjunction “and” is not correct)
3. A conditional clause presents a scenario or a condition that directs the rest of the sentence. The comma is placed after the scenario/condition and before the outcome.A
Examples:
- When she gets here, then the group will be seated.
- If he agrees, then we can make the purchase.
4. Commas are needed to add identify dialogue tags (“she said,” etc.) and to connect the words to their speaker.
Examples:
- “I like her portfolio of work,” she said.
- I said, “What is your favorite ice cream flavor?”
The only exceptions for this are when a question mark is required inside the quotation marks and the speaker is identified in the second half, not the first.
- “Do you like her voice?” he said.
5. One of the most welcomed attributes of a comma is its ability to wrap its arms around a clause. Any time a sentence veers off a comma helps wrap around that side tangent. Placing a comma essentially as bookends to the sentence’s “interruption” indicates the need for the reader to pause.
Example:
- The challenge, in the final phase of the basement remodel, was finding furniture that was in stock. (“in the final phase of the basement remodel” is an interruption, meaning you could remove that and not change the general meaning or intention of the sentence.)
- Melissa, of course, had a different opinion. (“of course” is the interruption here. It lends personality and flavor to the sentence, but could be removed without changing its meaning.)
If you read your writing out loud and there is the need for a pause, even a slight one, you most likely need to insert a comma. The comma seems like an innocuous little bit of punctuation, but it exists for a reason. So cue that mighty comma.