23 More About Commas
KEY CONCEPTS
Some comma usage guidelines require writers to use their judgment based on the context of a sentence instead of following strict rules.
Use of the Oxford comma, which is the comma separating the last two items in a list, varies among professional writing style guides and situations.
EXAMPLE: The store had sold out of milk, bottled water(Oxford comma) and canned food.
A writer sometimes needs to assess whether including or excluding an Oxford comma will affect the meaning of a sentence. You will study examples in this chapter.
You usually should insert a comma after an introductory phrase or clause at the start of a sentence.
EXAMPLE: While the author was writing this chapter, he sometimes struggled to write humorous examples.
MARKED VERSION: While the author was writing this chapter(introductory clause followed by a comma), he sometimes struggled to write humorous examples.
Supporting information about a noun or pronoun is often set apart in commas.
EXAMPLE: President Abraham Lincoln, the 16th president, died April 15, 1865, after being in a coma for eight hours.
MARKED VERSION: President Abraham Lincoln(comma), the 16th president(comma), died April 15(comma), 1865(comma), after being in a coma for eight hours.
Some comma guidelines provide clarity in writing but may not be absolute rules. That’s the case with portions of this chapter. As a result, the chapter does not include flip cards, but there is a closing practice exercise.
Here’s an opening example for a frequent debate about comma usage:
SENTENCE 1 – Each promotional bag included a coffee cup, a pamphlet and a hat.
SENTENCE 2 – Each promotional bag included a coffee cup, a pamphlet, and a hat.
What is the difference in the two sentences above? The answer involves an Oxford comma.
THE OXFORD COMMA
An Oxford comma can be used before the last item in a list. For example, here is the difference between the two previous sentences:
- NO Oxford comma — Each promotional bag included a coffee cup, a pamphlet and a hat.
- Oxford comma – Each promotional bag included a coffee cup, a pamphlet(comma), and a hat.
Journalists typically follow the Associated Press Stylebook, which says to “use commas to separate elements in a series, but do not put a comma before the conjunction in most simple series.” So most journalists would use the style of the first sentence above with no comma.
Some writers are passionate about either using or avoiding the Oxford comma. The comma between the last two items causes disagreements among professional and academic writers.
In most instances, the debate is only stylistic and does not alter a reader’s interpretation of the sentence. In either of the two sentences above, for example, it’s clear that the bag includes three items.
Occasionally, though, you may need to include or exclude the Oxford comma to provide more clarity. Let’s study a couple of examples.
The newly elected mayor thanked his mother, a local doctor, and his sister.
(It’s unclear whether his mother is a local doctor.)
In this case, an Oxford comma adds uncertainty about whether the mayor thanked two or three people. Is his mother a doctor, or is she just one of three people who received thanks? Removing the comma will make it clear that the mayor thanked three different people.
The newly elected mayor thanked his mother, a local doctor and his sister.
(The only interpretation is that he thanked three different people.)
Here’s a contrasting example:
The newly elected mayor thanked his parents, a local doctor and a local business owner.
(It’s not clear whether the mayor thanked only his parents or his parents and two other people.)
In the sentence above, do the mayor’s parents work as a local doctor and a local business owner? Adding the Oxford comma will make it clear that the mayor thanked four different people.
The newly elected mayor thanked his parents, a local doctor, and a local business owner.
(With the last comma added, the mayor more clearly thanked his parents and two additional people.)
The Associated Press Stylebook, as noted above, discourages the use of extraneous Oxford commas except when needed for clarity. Here’s verbatim guidance:
As with all punctuation, clarity is the biggest rule. If a comma does not help make clear what is being said, it should not be there. If omitting a comma could lead to confusion or misinterpretation, then use the comma.
However, some style manuals give conflicting advice. Grammarly provides additional perspective:
What is the Oxford comma and why do people care so much about it?
OPENING CLAUSES AND PHRASES
Let’s move beyond the Oxford comma to a clearer guideline for comma usage. When a sentence begins with a dependent phrase or clause, you typically follow it with a comma.
EXAMPLE: While the judge announced the decision, the defense attorney gasped.
Analyze the sentence as follows:
While the judge announced the decision(dependent clause followed by a comma), the defense attorney gasped.
Here’s suggested punctuation with an opening prepositional phrase:
EXAMPLE: In the chapter introduction, I asked you two questions.
Analyze the sentence as follows:
In the chapter introduction(prepositional phrase followed by a comma), I asked you two questions.
This guideline can also apply to adjectives or adverbs at the start of a sentence.
Tired and thirsty, the hikers returned to their base camp.
Carefully and skillfully, the surgeon completed the procedure.
However, if we rewrite the examples above, you often do not need a comma when the phrase, clause or other modifying words appear later in the sentence. These sentences do not need any commas.
The defense attorney gasped while the judge announced the decision.
I asked you two questions in the chapter introduction.
The tired and thirsty hikers returned to their base camp.
The surgeon carefully and skillfully completed the procedure.
MORE DETAILS ABOUT COMMAS
Depending on the sentence construction, commas may be used to set apart the following items:
- state names from cities
- the year in a calendar date
- ages
- job titles or other identifying information after a name
- Additional portions of some addresses.
In the following example sentences, note that commas appear both before and after the state, year, age and job title.
State name – He visited Denison, Texas, to learn more about the region’s economy.
Calendar date with a year – She was born on April 14, 1983, in Poteau, Oklahoma.
Age – Josh Inora, 32, became the youngest mayor in the city’s history.
Job title or other identifying information after a name – Josh Inora, the city’s new mayor, has scheduled a noon press conference.
Additional portion of an address – His listed address was 1245 Seminole Drive, Apt. 248, although he had not lived there for two years.
One common writing error is to forget the closing commas in instances such as the examples above. With that in mind, it’s worth repeating these examples for emphasis:
State name – He visited Denison(comma), Texas(comma), to learn more about the region’s economy.
Calendar date with a year – She was born on April 14(comma), 1983(comma), in Poteau, Oklahoma.
Age – Josh Inora(comma), 32(comma), became the youngest mayor in the city’s history.
Job title or other identifying information after a name – Josh Inora(comma), the city’s new mayor(comma), has scheduled a noon press conference.
Additional portion of an address – His listed address was 1245 Seminole Drive(comma), Apt. 248(comma), although he had not actually lived there for two years.
NONESSENTIAL ELEMENTS (review)
In a previous chapter about comma usage, we studied essential and nonessential elements. Related to that, you should use commas before and after a noun or pronoun that provides additional explanatory information. Here are two examples:
The 50th state, Hawaii, became part of the United States in 1959.
Steve Jobs, a co-founder of Apple Computer, died in 2011.
It’s worth emphasizing the second comma in each sentence again so that you avoid a common writing mistake:
The 50th state(comma), Hawaii(second comma), became part of the United States in 1959.
Steve Jobs(comma), a co-founder of Apple Computer(second comma), died in 2011.
If you need more explanation and practice with commas, here are resources from Purdue OWL:
MORE PRACTICE FOR PROFICIENCY
Below are additional usage questions based on this chapter. These questions may help you study for course assignments or a proficiency exam.
To view correct comma usage for the sentences in the practice exercise, click on the “Practice Answers” tab below.
WRITING EXERCISE
1. In one or two tightly written sentences, explain whether a journalist following AP style would include a comma after the word flashlight in the following sentence:
Each backpack included a water bottle, a flashlight(comma?) and insect repellant.
2. Using examples in this chapter as a guide, add additional information to the following sentence for Mary Stilwell’s age (45) and the state (Kansas) where Caldwell is located.
Mary Stilwell lives in Caldwell but spends several months each year overseas.
3. In two tightly constructed sentences, explain your key takeaway from this chapter. Do not use any first-person pronouns (such as I, me, my or mine) in your writing.
