Whether you are a person who sends the occasional email or a full-time writing professional, correctly using commas can be challenging. Yet, misplaced, missing or overused commas can mess up an otherwise good piece of writing, so mastering the basics of correct comma use is an important skill for all writers.
Courtesy of Purdue University’s Online Writing Lab (OWL), below are some common comma rules worth knowing and following.
1. Use commas “to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.”
The key here is “independent clauses,” which refers to parts of sentences that carry independent meaning and could be stand-alone sentences.
For example:
They decided to take back roads to the cabin, and promptly got lost.
This sentence strings together two independent chunks of meaning: (1) They took the back road to the cabin. (2) They got lost. The conjunction “and,” plus the addition of the word “promptly,” show the causal relationship between the two phrases, but the comma tells us that these are, indeed, two independent segments of action.
I was in way over my head, for I’d never hiked solo in such rugged terrain.
2. Commas should be used after introductory clauses, phrases and words. OWL states: “Common starter words for such introductory clauses include after, although, as, because, if, since, when, while.”
For example:
Because she was hiking with experienced mountaineers, she felt safe.
Although the weather turned the road to mud, our truck made it through.
3. In addition, there are three specific introductory words you should keep an eye out for, because they need to be followed by commas. These are: however, well and yes.
For example:
Well, he simply wasn’t what the company was looking for in a sales rep.
Yes, the climb will be challenging. However, our training will greatly help us.
4. Similar to setting off clauses at the beginning of sentences, commas also are used in tandem in the middle of sentences to “set off clauses, phrases or words that are not essential to the meaning of the sentence,” according to OWL. “Here are some clues to help you decide whether the sentence element is essential:
If you leave out the clause, phrase, or word, does the sentence still make sense?
Does the clause, phrase, or word interrupt the flow of words in the original sentence?
If you move the element to a different position in the sentence, does the sentence still make sense?
“If you answer ‘yes’ to one or more of these questions, then the element in question is nonessential and should be set off with commas.”
For example:
The meal, which was excellent, was served to us on the outdoor patio.
In this sentence the phrase “which was excellent” can be omitted without changing the meaning of the main sentence (that the meal was served outdoors on the patio).
A side note: clauses starting with “that” are almost universally considered essential clauses and therefore are not set off by commas.
For example:
That trout that Charlie hooked this morning was huge.
That storm that blew through yesterday tore some shingles off the roof.
5. Another common use of commas is to separate a series of three or more words, phrases or clauses.
For example:
Her children’s names were Kaila, Kassie, Kara, Kyle, Cameron, and Charlie.
However, this sentence could also be written without the comma before last item in the series:
Her children’s names were Kaila, Kassie, Kara, Kyle, Cameron and Charlie.
This comma nuance is the result of two different writing style guides: the Chicago Manual of Style and the Associated Press, or AP, style. Different writing styles use different style guides, and it is important to be aware of the right style for the piece you are writing. However, since this is an article on commas, we’ll leave the discussion of writing style guides for another time.
The above comma rules are among the most common ones. If you follow them carefully, you’ll be well on your way to mastering those seemingly capricious commas.
However, there is another batch of more nuanced comma rules to consider, and we’d be amiss keeping these from you. We will discuss them in a future Writers’ Guild Tips and Techniques newsletter.
Until then, may the flame of God Mercury be with you!
Thank you for the excellent summations of rules for commas, dashes, etc.!