Commas are the plague of writing, even for many professionals. There are a whole lot of rules, most of which have exceptions to the rule (or times when invoking the rule is a judgment call), many of which vary depending on what style guide you follow, and a lot of which require a basic understanding of some elements of grammar that, honestly, most of us kinda know by feel but can’t explain.
However, like all forms of punctuation, commas are crucial. The rules of punctuation aren’t just something made up by decrepit, persnickety English teachers whose only joy in life is making their students miserable. Punctuation is needed for clarity and comprehensibility of written text. How things are punctuated can change the meaning. Here’s an old joke:
A guy passes by a tailor shop and sees a sign in the window that reads, “My name is Fink what do you think I make suits for nothink.” Wow, the guy says to himself, a free suit? Can’t beat that. So he goes in, and Mr. Fink measures him carefully and talks with him about the merits of various fabrics and styles, and tells him to come back in two weeks. Two weeks later, the guy goes back and tries on the suit, and it’s gorgeous; it would be perfect for a prince. He thanks Mr. Fink and is about to walk out the door with his new suit, when Fink stops him and says, “That’ll be $5,000.” The guys is aghast: “But what about your sign?” And Fink replies, “Yeah: it says, ‘My name is Fink. What do you think, I make suits for nothink?'”
So, as good writers, to make sure our readers understand what we’re writing, we need to use punctuation correctly, including those pesky commas.
A lot of students have been taught that they should use a comma where they’d take a pause, and commas frequently do indicate a pause–but people pause for all sorts of reasons, not all of which have anything to do with grammatical sense. A lot of writers also look at commas the way inexperienced cooks look at salt: if something seems off, sprinkle some of that on there and it will fix things. Not true with salt in cooking; not true of commas with writing.
It’s really hard to keep all the rules about commas in mind, unless you’ve done an awful lot of writing and have looked them up a zillion times. In fact, I’ve done an awful lot of writing, and editing, and there are still some times when I need to check to see whether a comma is needed in a certain place. In a tutoring session, we would talk about where and how you use commas–and it’s easier to understand when you’re applying the rules to your own writing (and sense) than in the abstract. But here are some of the most common reasons to use a comma.
- To separate elements of a list (meaning three or more items). There is some debate about the “Oxford” (or serial) comma, which is the comma before the “and” at the end of a list, but as a general rule, I advise using it, unless you have a professor (or are in a profession) that specifically says not to.
- EXAMPLE: “I like bananas, grapes, and persimmons.”
- Between two independent clauses that are joined by a coordinating conjunction. (Do the who what now??) OK, breaking this down: “independent clauses” are things that can stand on their own as complete sentences, not sentence fragments. Coordinating conjunctions are the “BOYFANS”: but, or, yet, for, and, nor, so.
- EXAMPLE: “I like persimmons, so I buy them whenever I can find them in the stores.”
- NOTE: You can get away with doing that maybe twice in one sentence, but after that, you get into what we call “excessive coordination” and need to start breaking the sentence up.
- EXAMPLE (good sentence): I like persimmons, but they’re only briefly in season, so I buy them whenever I can find them in the stores.”
- EXAMPLE (excessive coordination): “I like persimmons, but they’re only briefly in season, and I’m never sure when I’ll find more, nor am I sure I’ll always find them in the same stores, so I buy them whenever I can, but they’re also expensive, and I need to be careful about my money, or I’ll be sorry by the end of the month.” (Note that that is technically not a run-on sentence: it has coordinating conjunctions where it nees them. It’s just a bit much of a muchness.)
- Note that in both the list arrangement and in the independent clauses joined by a coordinating conjunction, the comma goes before the conjunction, not after!
- After an introductory clause or phrase. This one is a bit of a judgment call, as a brief introductory bit may not need a comma.
- EXAMPLE: In 1929, the U.S. stock market crashed, causing a catastrophic economic depression.
- Note that the comma after 1929 is not strictly necessary in this case. However, when the introductory clause or phrase is longer, the comma becomes important.
- EXAMPLE: Because many people under the age of 30 in the U.S. don’t vote, voter registration drives on campuses are becoming increasingly common.
- Between the elements of a date in Month Day Year order. Note that no comma is needed if you only use the month and year, or if you put the date in Day Month Year order (as the Europeans do: they tend to be more logical about these things than those of us who got our culture originally from England).
- EXAMPLE: Although Pearl Harbor Day is set aside as a rembrance of the events of December 7, 1941, many people no longer make note of the date.
- Between the city and state when giving a location, and between street, city, and state when giving a street address.
- EXAMPLE: Zora Neale Hurston was born in Notasulga, Alabama.
- EXAMPLE: Mail your poems to Editors, 105 West 4th Street, New York, NY 10011.
- I hesitate to even mention this last one, as it requires a double layer of understanding, but commas are used around what are called “nonrestrictive clauses” in sentences. A nonrestrictive clause is a group of words that tells us more about something in a sentence but that isn’t strictly necessary to our understanding of that something. People now use “that” and “which” interchangeably, but technically, “that” is restrictive, and “which” is nonrestrictive.
- EXAMPLE (restrictive clause): The dog that was barking incessantly lived next door. (We need “was barking incessantly” to know which dog we’re talking about.)
- EXAMPLE (nonrestrictive clause): The dog on our lawn, which we recognized from its brown and white spots, belonged to our neighbors. (All readers really need to identify the dog is in the sentence without the further explanation of how we recognized it.)
- You can think of a nonrestrictive clause as something that you can plug into a sentence to add to it–and like a plug for a lamp, it has two prongs (the commas), unless, of course, it comes at the end of the sentence.
There are other places we use commas, but I figure, if you even got this far, your head is spinning and you wish I’d find something else to do with my time, so I’ll leave it at this. But commas, man. Argh!