Commas

Introductory elements are words or phrases that come at the beginning of a sentence, before the main clause. They often serve an adverbial purpose, meaning they indicate when, where, or how the action of the sentence happens. Commas are used to offset introductory elements from the main clause of the sentence. Examples:

In 2012, I started playing music. (the introductory element tells when the action happened)

On the ship, the sailors were cheering. (the introductory element tells where the action happened)

Swinging his arms, he ran toward the finish line. (the introductory element tells how the action happened)

Introductory elements may also be sentence modifiers, which do not really modify anything specific in the sentence. Instead, they serve more of an interjectory purpose (making an exclamation or interruption). Example: To be frank, I would prefer if you left.

Commas are used to join a dependent clause to an independent clause, but only if the dependent clause comes before the independent clause. Examples:

After finishing my homework, I played outside.                   I played outside after finishing my homework.

Because she was hungry, she ordered pizza.                       She ordered pizza because she was hungry.

Although he studied hard, he failed the test.                        He failed the test although he studied hard.


Commas are also used with conjunctions to join two independent clauses. Examples:

It started raining. We went inside. à It started raining, so we went inside.

He studied hard. He failed the test. à He studied hard, but he failed the test.

I like pizza. I also like tacos. à I like pizza, and I also like tacos.

A non-restrictive element is a word or phrase that adds extra information about something in a sentence (usually a noun) but is not necessary to identify that thing. A restrictive element, in contrast, is necessary to identifying the thing in modifies; taking it out of the sentence changes or obscures the meaning of that thing. Both non-restrictive and restrictive elements begin with words like which, who, where, and when. Non-restrictive elements are offset by commas; restrictive elements are not. Here are some examples of non-restrictive elements:

Amanda, who is my supervisor, gave me a raise. (the phrase who is my supervisor is not necessary to identify the noun Amanda—it simply adds extra information about Amanda)

I’m enrolled in Organic Chemistry, which is my favorite class. (the phrase which is my favorite class is not necessary to identify the noun Organic Chemistry—it simply adds extra information about it)

Forrest City, where I was born, is near the Tennessee border. (the phrase where I was born is not necessary to identify the noun Forrest City—it simply adds extra information about it)

In contrast, here are some examples of restrictive elements:

The woman who is my supervisor gave me a raise. (the phrase who is my supervisor is necessary to distinguish this particular woman from other women)

The class which is my favorite meets on Wednesday. (the phrase which is my favorite is necessary to distinguish this particular class from other classes)

The city where I was born is near the Tennessee border. (the phrase where I was born is necessary to distinguish this particular city from other cities)

Commas are placed between every item in a list to clearly separate the items and eliminate ambiguity. Examples:

I need eggs, milk, and peanut butter.

She is a smart, clever, and hard-working student.

We will eat pizza, tacos, sandwiches, or hamburgers.

Note: If items in a list include commas themselves, use semicolons instead of commas to clearly separate the items. Example:

I have traveled to Little Rock, Arkansas; Memphis, Tennessee; and Dallas, Texas.

A signal phrase includes the name of the author or speaker and either “according to” or a signal verb (e.g., writes, states, argues, claims). A signal phrase ends with a comma, unless it comes at the end of the sentence. It typically comes before the quotation but can also come after or even in the middle of it. Examples:

According to Gee, “One thing we build with language is significance” (98).

Gee writes, “One thing we build with language is significance” (98).

“One thing we build with language is significance,” according to Gee (98).

“One thing we build with language,” Gee writes, “is significance” (98).

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When do I use commas?

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