A common mistake I see people make in their writing is leaving out the second comma in parenthetical/nonrestrictive/nonessential words, phrases, or clauses.
I’m referring to that extra info that could be removed from a sentence without changing its meaning, which is often up to the writer to determine. Here’s an example:
“His mother, Kathleen, bakes the best birthday cakes.”
“Kathleen” is nonessential information for that sentence. If you remove it, the meaning of the sentence doesn’t change. “His mother bakes the best birthday cakes.”
One of the many things I love about fiction and creative writing is that authors can use commas more liberally to cause the reader to pause where desired.
Consider this sentence:
“Pete is going to the concert, unless it rains.”
“Unless it rains” is an essential part of that sentence because if it’s removed then Pete is going to that concert rain or shine! Furthermore, the meaning of the sentence doesn’t change if we remove that comma. The writer just chose to insert that comma to make the reader pause before moving on.
We run into a problem when a writer mistakes a parenthetical for a pause. “His mother, Kathleen bakes the best birthday cakes.”
If the writer is trying to insert an aside here, they need a second comma (after “Kathleen”). If they’re trying to create a pause, that gives us a messy sentence.
So. If you’re looking to add nonessential information midsentence, remember to insert both commas. If you’re intending to create a pause for your reader, be mindful of where (and how) you choose to do so.
Timothy