The comma sets off words and phrases in sentences to make the language more clear, making this punctuation mark among the most valuable. Unfortunately, because it does the complex work of separating items in a series, introducing phrases, and distinguishing relationships, using commas correctly can cause confusion.
Its use can accurately present meaning or completely alter it, as illustrated playfully in the book "Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation." Author Lynne Truss' title, with its errant comma, is based on a joke that appears on the back cover of her book:
A panda walks into a cafe. He orders a sandwich, eats it, then draws a gun and proceeds to fire it at the other patrons.
"Why?" asks the confused, surviving waiter amidst the carnage, as the panda makes towards the exit. The panda produces a badly punctuated wildlife manual and tosses it over his shoulder.
"Well, I'm a panda," he says. "Look it up."
The waiter turns to the relevant entry in the manual and, sure enough, finds an explanation. "Panda. Large black-and-white bear-like mammal, native to China. Eats, shoots and leaves."
With the comma, the panda does three actions – eating, shooting and leaving. Without a comma, the way it should have been written, the panda does one action – eats – and it consumes two foods – shoots and leaves.
While punctuation errors are unlikely to cause this level of disaster, your prose will look better and be more understandable with accurate comma usage. In this post, we'll look at some common comma errors:
Clauses and Commas
A simple way to determine whether to use a comma between two clauses separated by a conjunction is to decide whether the two clauses could each be a sentence on its own.
If so, this is a compound sentence with two independent clauses and should be separated with a comma:
Stephen King wrote a book, and he turned it into a TV miniseries.
If the sentence contains an independent clause followed by a dependent clause, it is a complex sentence and should not have a comma.
Incorrect: Stephen King wrote a book, and turned it into a TV miniseries.
Correct: Stephen King wrote a book and turned it into a TV miniseries.
Commas and Relationships
What if you refer to Stephen King's novel, "The Stand"?
Using the comma makes "The Stand" an appositive – a word, phrase or clause that renames a word in front of it, in this case "novel."
This would imply that King has written only one novel, which is far from true.
It would be correct to use commas if you referred to an aspect of the book – for example:
Stephen King's longest novel, "The Stand."
Not setting "The Stand" off with a comma makes "novel" an attributive noun – a noun that is used as an adjective. In this case, “novel” modifies “The Stand.”
So to mention the name of this particular novel in this case, it should be phrased as:
Stephen King's novel "The Stand."
Use a comma when a person's title comes after his or her name:
Stephen King, a horror novelist, is the author of "The Stand."
When the title is part of a phrase that includes that name, do not use a comma:
Horror novelist Stephen King is the author of "The Stand."
A comma splice occurs when two independent clauses are joined without a connecting word:
Incorrect: "The Stand" is an excellent novel, it has rich character development.
This sentence can be fixed by adding the word "and" after the comma, replacing the comma with a semicolon or dash, or starting a new sentence after the world "novel."
Correct: "The Stand" is an excellent novel, and it has rich character development.
Correct: "The Stand" is an excellent novel – it has rich character development.
Correct: "The Stand" is an excellent novel. It has rich character development.
The Forgotten Comma
A commonly dropped comma is the one that comes after a parenthetical clause, a phrase that's within a sentence but isn't essential to the meaning.
Incorrect: Stephen King, who uses Maine as the setting for many of his books wrote "The Stand" in 1978 and the screenplay for the TV miniseries in 1994.
To correct this, a closing comma belongs after "books" to close the phrase introduced by the comma.
Correct: Stephen King, who uses Maine as the setting for many of his books, wrote "The Stand" in 1978 and the screenplay for the TV miniseries in 1994.
On a similar note, the comma after the word "Maine" in Castle Rock, Maine, closes the phrase that shows Castle Rock within Maine.
Similarly, the closing comma in the phrase January 1, 2015, shows January 1 as part of 2015.
The Non-series Series
Commas are used to separate items in a list, but what constitutes a list? Many writers start a list with related items but end with an item that isn't really part of the list. Here's an example:
Incorrect: "The Stand" starred Gary Sinese, Rob Lowe, Molly Ringwald and gave Jamey Sheridan the role of the villain, Randall Flagg.
Sheridan is separate from the list of the other actors. Their names are associated with the verb "starred," while his name is associated with the verb "gave." An acceptable version of the sentence would be:
Correct: "The Stand" starred Gary Sinese, Rob Lowe and Molly Ringwald and gave Jamey Sheridan the role of the villain, Randall Flagg."
The Serial Comma
Since this post focuses only on comma errors, we will not belabor the serial comma, sometimes referred to as the Oxford comma. This is a comma placed before conjunctions such as “and” and “or” in a series of items – or not.
Acceptable: Stephen King's hobbies are reading, jigsaw puzzles and playing the guitar.
Acceptable: Stephen King's hobbies are reading, jigsaw puzzles, and playing the guitar.
A great deal of verbiage could be used to describe the often-heated debate between those who use the serial comma and those who do not.
For myself, I use the serial comma when it adds clarity. But, whichever way you want to do it, just be consistent.