Comma Usage at a Glance

Punctuation, one is taught, has a point: to keep up law and order. Punctuation marks are the road signs placed along the highway of our communication -- to control speeds, provide directions and prevent head-on collisions.

1.1 – Compound Sentences

Two or more sentences held together with coordinating conjunctions (for, and, nor, but, or, yet, so) form a compound sentence.  A comma must be used before the conjunction.

1.2 – Complex Sentences

Complex sentences contain on complete sentence and at least one fragment of a sentence.  Do not separate these parts with a comma.

1.3 – Compound/Complex Sentences

A compound/complex sentence contains two or more complete thoughts joined with coordinating conjunctions along with at least one sentence fragment.  Compound sentences require commas before the conjunctions.

1.4 – Introductory Elements

Some sentences begin with phrases.  Separate these phrases from the main part of the sentence with a comma.

1.4a – Using Transitional words

            1.4b – Dependent Adverbial Phrases

1.5 – Restrictive Clauses

Some phrases or clauses limit the meaning of the words they are referring to.  Because they are necessary to the meaning of the sentence, they should not be set off with commas.  

When you use who, which, whom, when, or where, decide whether the sentence would be unclear if you omitted it.  If omitting the phrase makes the sentence unclear or changes the meaning, then that part is necessary to the sentence, and you should not use commas.

1.6 – Appositives

An appositive renames the noun or pronoun it follows.  If omitting the appositive would change the meaning of the sentence, then do not set it apart with commas.  If the “renaming” does not change the meaning, then use commas.

1.7 – Parenthetical Comments

Parenthetical comments are those which can be left out but are included to add color or personality to the sentence.

1.8 – Items in a Series

Use a comma to separate words and phrases in a series.  Present usage advocates the use of the comma before and connecting the last two words of a series; some writers, however, prefer to omit the comma before and.  This comma is called the “series comma” or the “Oxford comma.”  When etc. ends a series, it should be preceded and followed by a comma.  Use commas to separate pairs of words in a series.  Use a comma between adjectives preceding a noun when they are coordinate qualifying words.

1.9 – Names

Use a comma to set off inverted names in bibliographies, in indexes, in directories, or in other reference lists.  Use a comma to separate a name from a title or a degree that it follows.  Use a comma to separate a name from a title or degree that follows it.

Do not use a comma to separate compound personal pronouns from the words they emphasize.  Omit the comma when an appositive has become part of the proper name.

1.10 – For similar or identical words

Use a comma to separate similar of identical words standing next to each other, even when the sense or continuity does not seem to require it.

1.11 – In direct quotations

Use a comma to set off direct quotations.  Not that no comma is needed in an indirect quotation.

1.12 – Short Phrases

A comma should follow yes, no, why, well when one of these words is used at the beginning of a sentence.  Use a comma to set off light exclamations.

1.13 – In Addresses

Use a comma to set off a phrase denoting residence or positions but not before ZIP codes.  Omit the comma before the ZIP code number in an address on an envelope; place the number two spaces after the two-letter state abbreviation.

1.14 – In Dates

Use a comma in dates.  A comma may be used to separate the month from the year when the date is omitted; in some current usage, the comma between the month and year is omitted.

1.15 – In Digits

Use a comma to set off figures in groups of more than four digits.

Use a comma to separate two figures or words indicating figures in order to make their meaning clear.