Comma Rules

Although there are specific rules governing how commas are used (see below), in general they are used to assist our readers in helping them understand how a certain sentence or passage should be read or understood.  We also use commas to help prevent confusion or misunderstanding.  If we follow these guidelines, clarity in writing is likely to improve dramatically.

Commas are generally used before conjunctions that begin independent clauses:

Example:

  • I thought it was impossible, but clearly I was wrong.

Exceptions:

  • She broadens her analysis by exploring the tragic elements of the play and by integrating her own unique style of writing.  (No comma is necessary; no pause is needed.)
  • Jim sings and John plays the piano. (Again, no comma is necessary since no pause is needed.)

Use a comma to separate clauses that are very alike, very short, or very casual:

Examples:

  • Here today, gone tomorrow.
  • Once bitten, twice shy. (These are grammatically correct, but the bigger issue is that these are both clichés,       and as such, should be avoided.)

Use commas to separate words, phrases, and clauses in a series:

Examples:

  • I love the old red, white, and blue.  (A distinct pause is necessary between “white” and “blue.”
  • John fed the pigs, watered the horses, and scooped the manure.

Use commas to set off parenthetical expressions:

Examples:

  • It was Mary, for example, who stole the show.
  • John Smith, a master of deception, was never convicted of a crime.

Use commas when setting off a specific name (direct address):

Example:

  • It’s up to you, Susan, to make me a better person.

Use a comma when starting a sentence with a conjunction (less traditional, but becoming more acceptable) or an adverb:

Examples:

  • Or, you can turn over a new leaf and try changing your ways. 
  • However, I wasn’t the only one who felt that way.

Again, the commas here are perfectly acceptable, and even quite necessary.

Use a comma after the common attribution "He said," "She said," or similar:

Examples:

  • When I spoke to John, he said, "Yes, we’ll all be there for dinner."
  • "You’ll be lucky to make it on time,” replied Sara.  “Traffic is crazy right now."
NOTE: Commas (and most other forms of punctuation) are placed inside the final quotation marks.