An appositive is a word or a phrase that gives extra information in a sentence. Because the extra information can be removed from the sentence without changing the meaning or the structure of the sentence, we place a comma on either side of the appositive.
Look at this example:
Bob, my neighbor, has a new dog.
The appositive is my neighbor. You could remove the words my neighbor and the sentence would still make sense: Bob has a new dog. However, the extra information about Bob being a neighbor helps us understand more about what is happening. Just remember that because the appositive is extra information, and can be removed, we need to place commas around the appositive.
Here are a few more examples of an appositive with commas on both sides:
Janet, my sister, is coming to visit.
Our teacher, Mr. Smith, loves to tell bad jokes.
Robert Frost, a poet, lived in New England.
Always use a comma before and after an appositive.
It’s your turn. Decide where you should put the two commas in this sentence with an appositive: John and Jim Dad’s brothers live on the next street. Did you figure it out? Good for you!