Commas

Punctuation serves as the traffic signal in our writing, indicating when to go, slow down, or stop.  Think of commas as a way to tell your reader when to pause for clarity, for emphasis, or for breath!

Commas are used in the following situations:

  1. To separate two COMPLETE IDEAS with a connecting word, called a conjunction (for, and, nor, but, or, yet so)
  2. To begin a sentence with an introductory word or phrase
  3. To set off an explanation
  4. To break up items in a list
  5. To introduce and end quotations

 

1. Separating Complete Ideas with a Connecting Word

A comma is necessary when a sentence has two or more phrases which are complete ideas.  It must also include a connecting word such as for, and, nor, but, or, yet, so.

This sentence has two complete ideas, so it needs to use a comma.

If the preceding sentence used a comma but didn't use the word "so," it would be a comma splice.

 

2. Beginning a Sentence with an Introductory Word or Phrase

If a sentence begins with an introductory word or phrase, put a comma after that word or phrase.

Introductory words could be things like afterwards, however, furthermore, in other words, meanwhile, still.

Meanwhile, the Surgeon General announced new guidelines.

They could also be adverbs (ending in –ly), like quickly, handily, softly, deftly, suddenly, unfortunately.

Confidently, the Surgeon General announced new guidelines.

The same goes for a sentence that begins with a phrase that includes a dependent marker word, also called a conjunctive adverb, such as after, although, as, as if, because, before, even if, even though, if, in order to, since, though, unless, until, whatever, when, whenever, whether, while.

At today's press conference, the Surgeon General announced new guidelines.

 

3. To Set off an Explanatory Phrase

If a phrase shows up in the middle of a sentence and provides an explanation or definition of the word or words in front of it, commas should go before and after the phrase.

The Surgeon General, an epidemiologist, announced new guidelines.

4. To Break Up Items in a List

Commas are used to break up items in a list.  It’s safest to use a comma between all of the items, including the last one, called the Oxford comma, though some people consider that last comma to be unnecessary.

 

The Surgeon General, the Secretary of State, and the President announced new guidelines today.

5. To Introduce or End Quotations

Commas should be used just after a writer introduces a quotation with a word like “said,” “wrote,” “shouted,” etc.  In addition, they should be used at the end of a quotation if the quote isn’t a complete idea.

"Today," announced the Surgeon General, "there are new guidelines.

 

This 5-minute video from TED lays out another way to remember when to use commas:

 

 





 

 

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