6.3: Commas

The Importance of Commas

The comma [ , ] is a handy punctuation mark that helps the reader pause between parts of a sentence. Commas can also help to clarify the meaning of our written words. There are many uses for commas, but we will cover four especially helpful uses here: introductory phrases, compound sentences, lists, and extra information.

Notice This!

😱 Jane enjoys cooking her family and dog. -- Jane likes to use her family and dog as ingredients to cook. Oh, no!

😊 Jane enjoys cooking, her family, and dog. -- Jane likes these three things. Everyone is safe.

Use a comma and save a life!

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1. Introductory Words and Phrases

Introductory word/phrase → comma → main clause

Use a comma after an introductory clause or phrase that comes before the main sentence. This tells the reader where the introduction ends and where the main clause begins.

• Yesterday, I studied until midnight. -- introductory word
• Because of the rainy forecast, I brought an umbrella with me to school. -- introductory phrase
• According to the textbook, researchers found a strong link between sleep and memory. -- introductory phrase
• Even though I would love to eat 5 pounds of chocolate everyday, it causes weight gain, clogs arteries, and contains caffeine. -- introductory dependent clause

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2. Compound Sentences (FANBOYS Coordinating Conjunctions)

Two sentences + FANBOYS → use a comma

Use a comma before a coordinating conjunction (for, and, nor, but, or, yet, so) if it joins two complete sentences (independent clauses). A complete sentence has a subject and a predicate (verb).

Caution

FANBOYS conjunctions can also join together two words or phrases. In these cases, you do not need a comma.

👍 Comma needed:

• Many students prefer to take notes on laptops, but others believe handwriting is more effective for learning.
• The experiment was successful, so the results were published in an academic journal.
• The Twilight films received negative reviews, yet many fans flocked to watch each movie multiple times in theaters.
• The witness neither confirmed the suspect's identity, nor did they offer any useful details.

❌ No comma:

• Many students prefer to take notes on laptops but not on tablets. --- "but" joins two prepositional phrases
• The experiment was successful and well-designed. --- "and" joins two adjectives
• The Twilight films received negative reviews yet generated over 3 billion dollars in profits combined. --- "yet" joins two verb phrases that share the subject "the Twilight films"
• The witness neither confirmed the suspect's identity nor offered any useful details. --- "nor" joins two verb phrases that share the subject "the witness"

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3. Lists or Series

List of 3 (or more) items → use commas

Use commas to separate items in a list of three or more. The comma before the last item (“and”) is called the Oxford comma, which is common in academic writing.

Oxford comma: I want to thank my parents, Spider-man, (Oxford comma) and Taylor Swift.

• I am clearly thanking four people: 2 parents, 1 Spider-man, 1 Taylor Swift.

No Oxford comma: I want to thank my parents, Spider-man and Taylor Swift.

• Am I thanking two people - my father Spider-man and my mother Taylor Swift?
• Or, am I thanking four people: 2 parents, 1 Spider-man, 1 Taylor Swift?

I personally prefer the Oxford comma because it ensures clarity, so I will continue to use it in the following examples.

However, you can choose to use the Oxford comma or not based on your personal preference and writing style. The key is to be consistent and either always use it or never use it.

More examples:

• I can take a chemistry, English, or math class this quarter.
• Computers have improved our lives tremendously by simplifying word processing, streamlining data storage, and promoting a global exchange of information.
• The writing process includes recursive, non-linear stages that writers can rapidly shift between: pre-writing, drafting, revising, polishing, and publishing.

No commas - only 2 list items:

• I can take chemistry or English the quarter.
• Computers have improved our lives tremendously by simplifying word processing and streamlining data storage.
• The writing process includes recursive, non-linear stages that writers can rapidly shift between, including pre-writing and revising.

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4. Extra Information

Extra information → commas around it

Use commas to set off extra information that is not essential to the meaning of the sentence. If you remove the extra information, the sentence still makes sense and contains enough information to communicate your main point.

Paris, the capital of France, is known for its art and history.

• Appositive: the capital of France

Recycling programs, though expensive at first, are ultimately an efficient and cost-effective means of reducing waste in our environment.

• Adverbial clause: though expensive at first

Last night, I got so upset playing a video game, which was called Hollow Knight: Silksong, that I ended up throwing my controller across the room.

• Relative (adjective) clause: which was called Hollow Knight: Silksong

The student submitted her essay, hoping to receive a high grade.

• Participial phrase: hoping to receive a high grade

I really enjoy watching super-hero movies, such as / including / like Batman, Guardians of the Galaxy, and the Avengers.

• Prepositional phrase: such as Batman, Guardians of the Galaxy, and the Avengers