Commas

Rule 1: Introductory Phrases

Use a comma after an introductory phrase or an adverbial clause that begins a sentence.

• For example, this sentence needed a comma.
• Once upon a time, there lived a wicked witch who loved to eat children for breakfast.

Rule 2: Dependent clause before independent clause

Use a comma after a dependent clause and before an independent clause.

Dependent clause markers include words such as: Because, Since, If, When, While, After

*See dependent clauses for more information

• After I began taking classes, I realized the importance of studying.
• Because he did not wear his raincoat, Matthew came home drenched to the skin.

Rule 3: Lists and the Oxford Comma

Use a comma to separate words in a series of three or more things.

 In academic writing, be sure to include a comma before the conjunction (known as the serial comma or the Oxford comma).

• I like apples, oranges, and bananas.
• The Doctor was accompanied by K-9, the Daleks, and his partner.

Rule 4: FANBOYS (Coordinating conjunctions)

Use a comma before a coordinating conjunction (and, but, yet, or, for, nor, so) to connect two independent clauses.

Never use a comma to connect two independent clauses without a conjunction. Use a semicolon, or start a new sentence.

• I thought I was finished with my paper, but I realized I’d forgotten to do my citations.
• I went to the animal shelter, and I found the perfect dog for my family.

• WRONG: I looked out the window, it had begun to rain.

• CORRECT: I looked out the window; it had begun to rain.

Rule 5: Parenthetical phrases (non-essential phrases)

Use a pair of commas to set off parenthetical phrases (non-essential elements) in a complete sentence. In other words, non-essential elements are phrases that can be removed from the sentence and the sentence still makes sense without it.

• I made an A, of course, because I revised my paper.

• Cassandra, his wife of nearly a decade, always managed to be right, although he never listened to her advice.

Rule 6: Contrasting phrases

Use a comma to set off phrases that express contrast.

• That backpack is mine, not yours.
• The Incredible Hulk is strong, but sensitive.

Rule 7:  Adjectives for the same noun

Use a comma to separate adjectives that modify the same noun in the same way.

• In order to get home, we must travel over several narrow, winding, treacherous roads.

Rule 8: Quotes

Use a comma to introduce quotes. When the quoted material contains more than four lines, it should be formatted as a block quote, and the comma should be omitted.

• The Professor said, “I will not tolerate plagiarism in my classroom.”
• Paul quietly looked at Jefferson and pointed out, “Your head is on fire.”

Rule 9: Locations, Dates, Titles, and Numbers

Use a comma:

• between a city and a state
• a date and the year
• a name and a title when the title comes after the name
• when writing out long numbers

• Hartford, Connecticut,
• June 15, 1997,
• Bob Downey, Professor of English
• 5,456,783 or $14,682

Rule 10: Avoiding Confusion

Use a comma to avoid confusion.

• Outside the ground was covered with hungry pigeons. -> This could mean the ground outside an area.
• Outside, the ground was covered with hungry pigeons. -> This means that you are inside and you are looking outside in to nature.