Commas can be tricky, and they can change the meaning of a sentence. Here’s a handy roundup of 5 common comma mistakes.
1. Missing commas to set off nonessential information
Example: Mrs. Johnson, who won the baking contest, lives in my neighborhood.
These commas are necessary because they set off information that interrupt, but doesn’t alter, the meaning of a sentence. The commas are there to show that the information is nonessential.
2. Unnecessary commas to set off essential information
Example: The woman who won the baking contest lives in my neighborhood.
Commas are unnecessary here because the information provided is necessary to understand the meaning of the sentence.
3. Missing comma before coordinating conjunction combining two independent clauses
Example: I wanted to go on vacation, but didn’t want to purchase a plane ticket.
The independent clauses here directly relate, and are joined by a coordinating conjunctions (for, and, nor, but, or, yet, so). When the conjunction is used to connect these two independent clauses, a comma must be placed before the conjunction.
4. Missing comma after introductory element
Example: Before eating, be sure you read the whole menu.
Here a comma calls attention to the opening idea, and follows the introductory word or phrase.
5. Missing comma in a series
Example with: I would like to thank my parents, Bill Clinton, and Oprah Winfrey.
Example without: I would like to thank my parents, Bill Clinton and Oprah Winfrey.
This comma is also called the Oxford comma, and clarifies the meaning when placed before conjunctions in a series of words in a sentence. Many don’t use the Oxford comma, but consistency reduces confusion – as seen above.