Daniel Schwen, GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/), via Wikimedia Commons
“A comma is just a coupler.”
“What’s that? A thing that makes couples?”
“I suppose so.”
Technically speaking, a coupler is the mechanism in the image above that connects one train car to the next. It also separates the train cars enough to keep them from knocking into each other. So, in a way, a coupler is something that makes couples. Another type of coupler is a comma (they almost look the same too). Commas can play the same role in a sentence–connecting or separating.
Within English, the comma has many roles and many uses, which can cause students trouble. Commas appear in writing a lot–almost as pervasive as the period–and since students see a lot of commas in writing, they tend to use the comma haphazardly whenever they are unsure what to do. If they feel like they need punctuation, but aren’t sure what kind, they use a comma. If students feel like they need to elevate their writing, but aren’t sure how, they use commas. This can be corrected, though.
The word “comma”, according to the Oxford English Dictionary, comes from the the Greek “komma” (κόμμα), which means “something cut off” or “a short clause”. The definition and origin of the word comma does hint at its purpose. But ultimately, as with any punctuation, a comma is a mark used to increase readability; a way to tell your reader how to read what you wrote–specifically, when to pause.
The comma is used in numerous situations in a sentence. Some of these situations require a comma and some of these situations depend on the choice of the writer. In this post, I want to focus on a the comma as a connector and separator. You’ll find that these are instances that require a comma, so no authorial choice here.
Comma + Coordinating Conjunction
A comma must accompany a coordinating conjunction when linking independent clauses. Instead of using a semicolon or a period to create a sentence that contains two subjects and two predicates, writers use words, like “and” or “but”, to join ideas and show their relationship.
So anytime that you find a sentence linked to another sentence with a coordinating conjunction (and, or, for, nor, but, yet, so), you must use a comma.
Ice cream is delicious, and I smile when I eat it.
The state fair begins tomorrow, but I think that I will go on the weekend.
Comma in a series or list
Another very common way to use a comma is to separate items in a series or list. The comma perfectly signals to the reader where one item ends and another begins.
The best ice cream flavors are rocky road, coconut, and dulce de leche.
Can you pick up eggs, a blue ball, nine apples, a piano seat, and eye glasses at the store when you go?
Debates rage over whether to put a comma before the coordinating conjunction in a list. That is the comma after coconut and seat in the examples above. I intend to write an entire article tackling this issue. For now, continue to do what you do, and if you don’t have something that you regularly do, start including the comma after the conjunction.
Comma with equal adjectives
Just like in a list of items, a comma should also be used when you have a list of equal adjectives. Equal adjectives are generally less common than other adjectives, like colors, numbers, and shapes, and each adjective equally and individually modifies the noun. However, with the more common adjectives, which tend to stack on top of each other, each one describes the next in turn, until arriving at the noun.
The deft, nimble, aged hands of the carpenter quickly whittled a small doll for the young girl.
In the sentence above, the words deft, nimble and aged each describe hands. The best way to know if you are using equal adjectives is to reorder the adjectives (“aged, deft, nimble hands”). If your phrase still makes sense, then use commas. Another test is to read your phrase with “and” inserted between the adjectives (“deft and nimble and aged hands”). If it makes senses, then they are equal adjectives. If it sounds strange, they are not equal, and you will not use a comma. For example:
I ate three red apples.
In the sentence above, if you reorder the adjectives three and red, the sentence will sound very strange (“red three apples”). Also, if you place the word “and” between them (“three and red apples), the sentence will sound strange. Thus these adjectives should not be separated by a comma.
The rules governing comma usage are extensive. We have only touched on three so far. Next week, another article on commas will look at some of the other comma rules.
The series on commas continues: “Comma Usage: For Spicing It Up.”