Commas are important, because they separate the parts of a sentence into clear segments. It takes a conscious effort to translate the rhythm of a sentence into writing using punctuation. The comma often marks a brief pause in the flow of a sentence, and helpfully distinguishes one phrase from another.

The comma helps the reader, and without it the reader would often have to go back and reread a sentence to find out exactly what the writer meant.

The Comma often helps set off interrupting matter within sentences. Many writers don't realize that they are setting off a phrase, so they begin with the first comma but omit the second, which should conclude the parenthetical matter. Check for this sort of thing in your proofreading.

A standard use for commas is in separating the items in a series: knives, forks, and spoons. Authorities differ as to whether that final comma before the and is required, so you can use your judgment.

Following this brief introduction, use the following rules for clear and correct writing:

1.) Use commas to separate independent clauses when they are joined by any of these words: and, but, for, or, nor, so, yet.
i.e. The class was over, but the teacher would not finish talking.

2.) Use commas after introductory clauses, phrases, or words that come before the main clause. Introductory clauses that should be followed by a comma include: after, although, as, because, if, since, when, while.
i.e. While I was jogging, the rain would not stop.

3.) Use a pair of commas in the middle of a sentence to set off clauses, phrases, and words that are not crucial to the meaning of the sentence.
i.e. My favorite desert is ice-cream. My brother, however, prefers chocolate cake.

4.) Use commas to separate three or more words, phrases, or clauses written in a series.
i.e. Angie, Dan, and Tina went to school.

5.) Use commas to set off all geographical names, items in dates (except the month and day), addresses (except the street number and name), and titles in names.
i.e. Los Angeles, California is a dynamic city.

6.) Use commas wherever necessary to prevent possible confusion or misreading.

7.) Don't use a comma to separate the subject from the verb.

8.) Don't put a comma between the two verbs or verb phrases in a compound predicate.

David Brown