Comma Usage

Simple Rules for Using Commas

1.  Use to separate items in a series, even if the items are groups of words.  A series is three or more items.

    Example: Bullets flew over our heads, ricocheted off the walls, and broke windows.

Use a comma before “and” when you get to the last item in the series.  Doing so prevents possible confusion.

    Example: Soil types include clay, loam, coarse sand, and gravel.  (Without the final comma the phrase would read “coarse sand and gravel” and would make one wonder if the soil is coarse sand mixed with gravel, or if it were two separate items.)

2.  Separate two or more adjectives preceding a noun with a comma.

    Example: She repainted the large, pink room.

    In nouns where an adjective acts as a part of the name no comma is needed.

    Example: Big horn sheep, electric light.

    If you’re not sure, test by placing the word “and” between these sorts of nouns.  If it sounds awkward, don’t use a comma.

    Example: Big and horn sheep

3.  Use a comma before “and”, “but”, “or”, “nor”, “for”, and “get” when they join the parts of a compound sentence.  Remember a compound sentence is two or more simple sentences.  A simple sentence has a subject and a verb.

    Example: John ran track, and Mary cheered from the stands. (Subject: John; verb: ran; conjunction: and; Subject: Mary; verb: cheered.

    Compound verbs and compound subjects generally do not have commas separating them, unless they are items in a series (see number 1).

    In the above example we could alter the sentence slightly to have a compound subject: John and Mary cheered from the stands. 

    We could also alter it slightly to be a compound verb: John ran track and afterwards cheered from the stands.

4.  Commas set off phrases that interrupt sentence flow. 

    If the appositive (means the same thing or person), direct address (a specific name in dialogue), or a parenthetical expression (words and phrases such as “in my opinion”, “of course”, “by the way”) comes at the beginning of the sentence, use a comma afterward; if it comes at the end of the sentence, use a comma before; otherwise use a comma on both sides of the expression.

    Example: Willie, my brother, lives two states away. (appositive)

    Example: “John, duck!” (direct address)

    Example: “Based on the criminal’s past history, in my professional opinion, a sentence of five years probation would be appropriate.” (parenthetical expression)

5.  Other standard comma usage.

    a) separate items in dates

    b) separate items in addresses

    c) after salutations in a letter

    d) after the closing of a letter before the signature

    e) after a speaker is finshed speaking in dialogue add a comma just before the end quotation marks before the dialogue tag

DO NOT INSERT COMMAS when you take a breath.  This creates comma splicing which you should avoid.  If you follow the guidelines set above, you’ll have few, if any, comma errors.