In my second year of junior college, I took a World Religions class that I absolutely loved. When our midterm paper came around, I threw myself into it. I thought I had some great ideas in that paper. But the teacher gave me a D.
When I asked him what had gone wrong, he told me that my ideas were decent, but I didn’t know how to use commas. I couldn’t believe I’d been marked down that much for punctuation errors. The paper was about religion, not punctuation, after all. The professor offered to go over some basic comma rules during office hours. I went, and while I may not have mastered the rules in the room that day, the time that teacher took with me changed how I wrote. From that day forward, the MLA handbook was always by my side when I was writing a paper.
Over time, not only did the rules stick, but I became passionate about how punctuation helps the reader understand the relationship between ideas.
Think of commas as the simplest way to express compounding ideas, whether they be multiple items in a list, multiple subjects, descriptions, or introductions.
Keeping that in mind, let’s look at five instances that require a comma:
1. Serial comma
The serial comma, sometimes called the Oxford comma, is used to separate items in a list.
Ex: Ana ate a hamburger with pickles, mustard, and ketchup.
If the sentence carries on after the last item in the list the same rule applies.
Ex: Ana ate a hamburger with pickles, mustard, and ketchup for lunch.
The exception to the rule is when the last two items in the list can be read as a pair.
Ex: Brian asked for chips, an apple, and peanut butter and jelly.
The serial comma is perhaps the most controversial type of comma out there. Most style guides, such as The Chicago Manual of Style, suggest using it; whereas others, like the AP Stylebook, which journalists and marketers use, don’t require it. The thing to keep in mind is clarity. Think the controversy is much ado about nothing? Check out this instance where the lack of a serial comma cost a Maine dairy $5 million.
2. Joining Sentences aka Independent Clauses
Independent clauses, or complete sentences, can only be joined using a comma when there is a coordinating conjunction involved. There are seven coordinating conjunctions and they can be remembered using the acronym FANBOYS (for, and, nor, but, or, yet, so). If one of these words isn’t joining your clauses, then you have to find a different piece of punctuation, such as a semi-colon.
Ex: We went to the new restaurant on Main Street last night, but it was closed for a private party.
Ex: I wanted to go to Macy’s to buy shoes, and Sheila wanted to get a pretzel, so we went to the mall.
The only time when this rule doesn’t apply is when the sentence is short.
Ex: Justin played the piano and Bailey sang.
3. Commas with Introductory Dependent Clauses
An introductory dependent clause occurs when the action of the main clause depends on the action of the introductory clause. If/then statements are great examples of a sentence with an introductory dependent clause.
Ex: If you do the grocery shopping, I’ll cook dinner.
In the sentence above, the then is implied, and it is unnecessary to include it.
Dependent clauses are often introduced by subordinating conjunctions like if, because, when, whether, and until.
Ex: Whether you believe her or not, she’s telling the truth.
Ex: When your father gets home, he’s going to be mad.
4. Descriptive phrases
This is a great place to talk about restrictive and non-restrictive phrases. If a phrase is essential to understanding the identity of the noun it’s referring to, then it’s called a restrictive phrase. In the case of a restrictive phrase, a comma should not separate the noun from the identifying phrase.
Ex: The guy with the skateboard under his arm is my brother.
However, if the phrase is not essential to understanding the identity of the noun, then the phrase should be set off by commas both before and after.
Ex: My brother, with his skateboard under his arm, walked over to where I was sitting.
If the sentence can be understood when the descriptive phrase is taken out, then the phrase needs to be set between commas.
5. Commas with two or more adjectives
This one is tricky because not all sentences with two or more adjectives take a comma. The ones that do contain coordinating adjectives. Coordinating adjectives can be separated by the word and instead of a comma and can be reversed in order and still make sense.
Ex: John had proved a dishonest, manipulative leader. (John’s leadership has proved dishonest and manipulative)
Ex: It’s going to be a long, dark, cold winter in Alaska. (Winter in Alaska is going to be long and dark and cold.
If your string of adjectives isn’t coordinate, it might be compound. But that’s a lesson for another day.
I hope you’ve found these comma rules easy and helpful. If you have more questions about commas, or anything related to grammar and punctuation, send me an email.