There are not too many forms of punctuation that can cause such a furor as the lowly comma. Most writer understand its use as a tool of language, but some of us just chose to skip that day in English. Either that or the teacher did. I’m stunned in both the classes I teach and the manuscripts I’m asked to critique that there is such a blatant misuse of this form of punctuation. They get stuck in places where they have not business being, left out of places where they are desperately needed, and are the one thing I spend the most time discussing when my students get their essays or manuscripts handed back to them.
“So what’s the big deal?” you might be asking. “They’re only commas.”
In truth, commas are one of the most powerful forms of punctuation. Simply putting one into a sentence can completely change the meaning of the whole sentence. The book “Eats, Shoots, and Leaves” presents several marvelous examples illustrating just this point. To paraphrase an example from the book, consider the following sentence which is improperly punctuated:
“Edith walked on her head a little higher than before.”
Clearly we do not mean to imply that Edith sprouted feet from her scalp. Now, let’s add a comma, but in the incorrect place.
“Edith walked on her head, a little higher than before.”
Either we are suggesting that Edith did grow feet from her scalp, or she is using illegal substances and is hallucinating the whole thing. If we simply move the comma to the correct location, it all becomes perfectly clear:
“Edith walked on, her head a little higher than before.”
Now it’s clear what the writer intended to say about Edith, and it has nothing to do with a scalp condition or hallucinogenic drugs.
Commas are used to separate thoughts, to show which things are connected and which are not. For example, the writer may choose to open a sentence with a prepositional phrase. This phrase not being a complete sentence, it must be separated from the independent clause by a comma. For example:
“After dancing into the night, Cinderella suddenly noticed the late hour.”
Here, the second half of the sentence is a complete thought – an independent clause – which is being introduced by a prepositional phrase (the word “after” is the preposition). The introductory phrase is there to give the reader a little more detail, but the main topic of the sentence comes after the comma.
Commas connect a string of independent adjectives, too. First, the improperly done sentence:
“That is one big ugly smelly pink flower.”
By running all the adjectives together, the writer says to the reader that if the flower were not big, it wouldn’t be ugly; that if it weren’t ugly, it wouldn’t be smelly; and, if it weren’t smelly, it wouldn’t be pink. Clearly, the color has nothing to do with the smell, the size has nothing to do with the attractiveness. Here, then, is the correct version:
“That is one big, ugly, smelly, pink flower.”
Commas used with conjunctions get a little pickier. It depends on what you’re joining with your conjunction, and the structure of your sentence. For example:
“I would like to have a large chocolate milkshake, and I will need two straws.”
The comma separates two independent clauses – sentences that can stand by themselves if separated. The comma is used before the conjunction to show that this is the joining of two independent ideas.
“Fred washed his socks in the laundry and hung them to dry on the line.”
Here there is no comma because we have a “compound predicate” – two verbs (washed, hung), but only one subject (Fred). The second half of this sentence could not stand as a complete thought or complete sentence on its own. You wouldn’t write a sentence that said “Hung them to dry on the line.”
“I want a peanut butter and grape jelly sandwich.”
No commas here because you are joining two nouns of equal value (“peanut butter” is one noun, “grape jelly” is the other).
For comments that are parenthetical – information that is extra, but not essential, to your sentence – commas are used in place of parentheses to show the reader that this information isn’t as important as the rest of the sentence.
“Julia, the annoying cheerleader in the white skirt, is as phony as fake vomit.”
The information between the commas is just extra, for clarification. If you remove it from the middle of the sentence, the sentence will still make complete sense. We do this with clauses that begin with who, which, or that also. For example:
“Marge Elving, who is the club’s secretary, made her report to the committee.”
“Floyd’s green Buick, which was totalled in the wreck, was worth less than he owed on it.”
Again, these clauses provide extra information, but if they were to be taken out of the sentence, the reader would still get the basic idea.
There are a number of excellent books available to help with learning to use the comma. I can highly recommend “The Brief Handbook” that is available at most college book stores. Strunk and White’s “The Elements of Style” is also a great resource, and it only costs a few dollars at any book store anywhere. “Eats, Shoots and Leaves” is not only informative, it’s very funny.
Many people did not get a thorough understanding of this in school, and in some cases, you may not have had a teacher that even knew this. The good news is that it is never too late. Keep one of these resources handy, just like a dictionary, to make sure you’re following the right setup when you right. We all make mistakes, but at least now you can minimize them!