First, let me state that what I am about to share is not all of the comma usage rules. What I share here are the comma usage rules that cause confusion when not used effectively.
Now, let me go on to state that some comma usage choices are not based upon rules, but rather guidelines that leave the usage up to the writer’s preference. You are the writer, so write in a way that makes your content clear to the reader. If adding a comma adds clarity, by all means, place that comma exactly where you deem it needs to be.
Using Commas Effectively
Alright, in order to use commas effectively, you need to have a handle on the purpose of the comma. The purpose of the comma is to indicate a brief pause in a sentence. A comma lets the reader know that there is more to follow.
Effective Comma Use #1: Use commas to separate words in a series of three or more items. Example:
I like ice cream, cake, and candy.
Note: Some grammar professionals suggest that the final comma can be omitted from the series. Whether you place the comma before the final item in the series or not is up to you, however either way you decide to use the comma, just be consistent throughout your work.
I like ice cream, cake and candy.
I like ice cream, cheese and crackers and candy.
To omit the comma in the last item in a series (as in the last example shown) might cause confusion. People, who are not familiar with common food dishes, may think cheese and crackers and candy is one item. It would be best to include the comma for clarification in a way that is similar to the first example.
Effective Comma Use #2: Whenever you have two adjectives in a sentence, and whenever those adjectives can be used interchangeably, then use a comma to separate the adjectives.
Alice ate the delicious, ripe apple.
Note: The adjectives (delicious and ripe) can be used interchangeably in the sentence, so a comma is appropriate to separate them.
Effective Comma Use #3: Expressions such as nevertheless, after all, however, by the way, in other words, etc. are words that tend to interrupt the flow of the sentence. Use a comma to set off the expression.
He is, by the way, very handsome.
Effective Comma Use #4: The use of independent clauses can cause many a heated conversations. The most acceptable rule is that when a sentence is started with a dependent clause, use a comma after it.
If it rains tomorrow, call before leaving.
Effective Comma Use #5: When a subject is clearly identified, then the description that follows that subject is not really essential and should be set off by commas.
Aunt Mary, the multimillionaire, lives in a mansion on the hill.
If your readers are already familiar with who Aunt Mary is, then explaining that Aunt Mary is a multimillionaire is non-essential. The explanation should be set off with commas.
On the other hand…
That elderly lady who is a multimillionaire lives in a mansion.
Since the readers do not know who the lady is, the explanation that follows is essential and does not need to be set off with commas.
Effective Comma Use #6: Use commas with direct quotations.
Mary Ann said, “This is it!”
“So,” I said, “you can have it your way.”
There Are More Comma Usage Guidelines
There are many more comma usage guidelines to explore. The guidelines shared today are guidelines that tend to be the most confusing and cause the most heated discussions among writers, subject matter experts, and publishing managers.
When I need answers, I refer to resources that have served me well as a technical writer in the past and as a freelance writer now. The following books sit on my bookshelf ready for use at my demand. When working with clients, you will need to adhere to the client’s style guide for how they want their documents to be formatted. As an independant writer, you have the liberty of setting up your own style guide. The following resources offer excellent information on grammar and punctuation styles that are most common to writing for United States publishing standards.
For more in depth information and to find more comma usage guidelines, explore the following resources that I use on a regular basis. These books can be found easily an most retail bookstores.
Strunk and White’s The Elements of Style
The Chicago Manual of Style
Next Writing Tip
I will approach the subject of “Quotation Marks” and how to use them correctly.
Until then, happy writing!