When it comes to proper comma usage, the advice out there can range from complete avoidance to complete saturation.
I once heard a professor of English say, "Commas are a complete mystery to me, so I just leave them out." At the other extreme, almost all of us have heard at least one time or another, "Every time you take a breath, put a comma there." If you do not want to avoid commas completely but also want to avoid complete comma saturation, here are a few guidelines that will help you decide where to put that confusing little squiggle.
I once heard a professor of English say, "Commas are a complete mystery to me, so I just leave them out." At the other extreme, almost all of us have heard at least one time or another, "Every time you take a breath, put a comma there." If you do not want to avoid commas completely but also want to avoid complete comma saturation, here are a few guidelines that will help you decide where to put that confusing little squiggle.
1) Know Your Clauses
If the word "clause" scares you or only brings up images of Christmas, then you may first need to ask yourself how you know when a sentence is a sentence. Though there are always exceptions, a sentence is a group of words that contain a subject and a (conjugated) verb that together express a complete thought.
If your group of words fits this description, you have an independent clause. What, you may ask, is a "complete thought?" This is where your feeling or intuition plays a role; you just sense that it is.
If the group of words contains a subject and a verb but does not express a complete thought or cannot stand alone, you have a dependent clause. Dependent clauses often contain a dependent marker word, such as "because," "although," or "since."
If the group of words is missing a subject or a verb, it is considered a fragment.
2) Compound Sentences
You can use commas to separate clauses in a single sentence. If you want to combine two independent clauses, use a comma followed by one of seven conjunctions (and, but, or, for, nor, yet, so).
Example: I am going to the store, and my brother is cutting the grass.
Use a comma to separate dependent clauses that precede independent clauses. If dependent clauses follow independent clauses, commas are usually not required.
Example: Because my brother is cutting the grass, I am going to the store.
Generally speaking, you are only allowed a maximum of two independent clauses in one sentence. Exceptions can be made, but be wary of packing too much information into one sentence.
3) Series
Any series that contains three or more items should be separated by commas. There is some debate about whether to put a comma before the final item in the series. The general wisdom is to pick one method and use it consistently throughout the paper.
4) Non-essential Elements
Groups of words that are not essential to the meaning of the main clause should be set off by commas. These would include interjections, appositives (renaming a noun), and quotations.
5) Geographical Names and Dates
These are sometimes overlooked. Remember that a comma should separate cities from states, but they should also separate cities and states from countries.
Example: The Purdue Writing Lab is located in West Lafayette, IN, USA on the campus of Purdue University.
Commas should separate the day of the week from the date and month and the date and month from the year. They should NOT separate the date from the month.
Example: The conference begins on Friday, October 11, 2008.
6) Now It's Your Turn!
Add Your Simple Comma Guideline (not rule) to Our Five Minute Lesson
As Learning Advisers at the University of South Australia, we see lots of student work which has grammar errors ranging from minor to gob-smackingly enormous!