10 Comma Rules
1. A comma comes before a coordinating conjunction (FANBOYS) when both are independent clauses.
- CORRECT: I would love to go hiking, but I have to study organizational communication.
- INCORRECT: I would love to, but I have to study.
EXPLANATION: In the correct sentence, both sentences in bold are independent clauses. An independent clause has both a noun and verb and can stand on its own. A dependent clause cannot stand on its own, it does not express a full thought, it is also known as a fragment. The FANBOY (for, and, nor, but, or, yet) which in this case is but and separates two independent clauses. In the second sentence labeled incorrect only has ONE independent clause and not two. The first half of the sentence is a fragment. This person would love to do what? It doesn’t express a full thought.
2. A comma comes after an adverb clause only at the beginning of a sentence—not at the end. Usually starts with after although, as, if, because, until, when, et
- CORRECT: Although I would like to go hiking, I must study organizational communication.
- CORRECT: I must study organizational communication after we go for a hike.
- INCORRECT: I would like to go hiking, because I don’t want to study communication.
- INCORRECT: I will study communication, until we go hiking.
EXPLANATION: An adverb clause is a clause that starts with an adverb which will start the sentence or ends the sentence. The first correct example, there are two independent clauses separated by a comma. The second example is flipped so there is no comma. The first incorrect example shows a comma before because it creates extra wordiness. Everything after the “because and comma” is just extra information that is usually not needed.
The only time you break this rule is when the writer is trying to eliminate confusion for the reader. Eliminate the comma or if you want to eliminate because, don’t insert a comma either between two clauses creating a comma splice. The second incorrect example has an adverb in front of the comma. Adverbs coming at the end or middle of the sentence don’t need commas to introduce the next clause in the sentence, the adverb already does that.
3. A comma comes after a conjunctive adverb that follows a semicolon.
- CORRECT: I must study organizational communication; therefore, I can’t go hiking with you.
- OR: I will study organizational communication; and then I will go hiking.
- INCORRECT: I must study organizational communication; therefore I can’t go hiking with you.
- OR: I will study organizational communication and then I will go hiking.
EXPLANATION: A list of conjunctive adverbs are: finally, furthermore, therefore, moreover, next, however, likewise, thus, then, otherwise, etc. For the first correct example, therefore is used, a semicolon, and a comma. Whenever a conjunctive adverb follows a semicolon, it must be followed by a comma. With the second example, whenever a “then” is after a comma, a “and” must go in front of the “then” or else it makes the clause a fragment. The incorrect sentences are missing commas or semicolons.
Try reading the correct and incorrect sentences with the appropriate pauses and see what sentences sound better when spoken and written.
4. A comma coming after an introductory element.
- CORRECT: After my online test, I can go hiking.
- INCORRECT: After my online test I can go hiking.
EXPLANATION: An introductory dependent clause used in the correct example begins or “sets the stage” for the independent clause. Without a comma it turns into a fragment and the emphasis the writer put on “After my online test” is lost. The natural pause and effect is also lost.
5. Comma can be used to separate items contained in a series. The series needs to be three or more.
- CORRECT: I study Lincoln, Kennedy, and Garfield.
- INCORRECT: I study Jupiter, Saturn.
EXPLANATION: The three or more list allows the reader to understand if list keeps going, or the writer has ended the list. The incorrect example shows a fragment with Saturn, it’s only one word and not a complete thought. To fix it would be drop the comma and add “and” to finish the list. It is all about starting, continuing, and ending lists with this comma rule.
6. Two adjectives are separated where an “and” or a “dash” can go.
- CORRECT: “Green, black river”
- CORRECT: “Green—black river”
- INCORRECT: “Green black river”
- INCORRECT: “blue, wool sweater”
EXPLANATION: If the adjectives are alike, like colors in the examples then they are coordinate adjectives. The writer or editor can test two ways if there needs to be a comma between two adjectives. The first test is placing an “and” between the adjectives, and switching the adjectives around like this, “black and green river.” If the sentence still makes sense then the "commas," "dashes," and "and's" are appropriate to use in order to separate the coordinate adjectives. (I lived next a) green, black river (that always flooded in the spring).”
For the incorrect sentence for the test it is wool blue sweater. The phrase sounds strange, meaning the adjectives are not coordinating and don’t need a comma or dash. The phrase sounds correct with “(I ruined the) blue wool sweater (I wore last week when I got grease on it from cooking).”
7. Using commas in dates and addresses.
- Saturday, Feb 11, 2017 May, 2017
- 11 May, 2017 Paris, France
- 11 October 2017 Paris, France, during May, 1995
EXPLANATION: When using either Style, which is the first and third example on the left, either commas or no commas. All of these examples are correct, but in many different forms. These forms are standard all over the world. American are the first two, the last is modern American and European.
8. Commas are used to set off information that is extra in a sentence.
- SEVERAL: My friend, Nate, graduated from college.
- ONE: My brother Matt loves motorcycles.
EXPLANATION: The first example implies the writer has many friends, specified by the comma “My friend, Nate” referring to which friend. The second example signifies only one person with no comma, if there was a comma between “brother” and “Matt” then it would mean this person has more than one brother.
9. Using commas in quotations:
- My mother said, “Clean your room.”
- “I must clean my room,” I said. “My mother said so.”
- “Don’t interrupt me! I’m cleaning!” the kid shouted.
EXPLANATION: All of these forms are correct. To keep in mind is the comma. The comma must have an independent clause before or after. The third example for capitalizing the “the” is up to the writer. It does not have to be capitalized. It can be a purely stylistic choice.
10. Avoid comma splices, which a comma to separate essential elements of a sentence.
- CORRECT: My friend and I hiked for three days. We were very tired.
- OR: My friend and I hiked for three days; we were very tired.
- OR: My friend and I hiked for three days, so we were very tired.
- INCORRECT: My friend and I hiked for three days, we were very tired.
EXPLANATION: A comma splice is created when a comma goes in between two independent clauses or otherwise known as essential elements. There are five ways to fix this: (One), put a period where the comma is, (Two), use a semicolon instead, (Three), use a semicolon, coordinating conjunction, (fourth), semicolon, conjunctive adverb, comma, (fifth), change one of the independent clauses to a dependent or fragment.