Commas

Commas are a very useful punctuation mark, but it can get a bit confusing as to when to use them. Here are some times to use commas.

First, when you have and, but, or, nor, for, so, or yet linking two parts of a sentence that can can each stand on their own, you need a comma before the linking word.

Example: Learning is fun, but I would rather read a novel.

A caution: Sentences that use the linking words but where one of the two parts of the sentence cannot stand on its own do not use comas.

Example: Bob was sick today and stayed home.

Second, if you have an introductory word or phrase beginning the sentence you need to set that off by a comma as well. Note: The person or thing the sentence is about is not an introductory phrase.

Example: Fortunately, the teacher gave an extension on the assignment.

Third, if there is a nonessential element in the middle of the sentence it needs to be set off by commas. A good test for this is removing the part in question and see if what remains has the same meaning. If it does, commas are needed.

Example: Albert Einstien, who ended his career at Princeton in the United States, was born in Germany.

Example: Those who had not watched Lost from the beginning felt left out when the series finally concluded.

Fourth, use commas to separate items in a list (unless the items in the list already have commas – then use a semicolon). A comma before and is optional but is usually clearer. Note: Do not use commas around the list, only in the list.

Example: Strawberries, peaches, and clementine oranges are some of my favorite fruit.

Fifth, use a comma between adjectives when each one describes the same word equally. A good test for this is is if the two adjectives could be joined by the word and.

Example: Sandra Bullock deserves her Oscar for her understated, sincere performance in The Blindside.

Sixth, there are a lot of places where commas are needed such as long numbers, dates, and addresses.

Example: The zen librarian googled nothing and got 5,214,693 hits.

Example: The Declaration of Independence was signed July 4, 1776.

Note: If the date had been at the beginning of the sentence, another comma would have been needed between the year and the rest of the sentence.

Example: The fictional Sherlock Holmes lived at 221B Baker Street, London, England zip unknown.

Sixth, use a comma to set off quotations. Note: If the quote is split between two parts that can stand on their own, use a semicolon or period instead.

Example: A Tale of Two Cities by Charles Dickens begins, “It was the best of times, it was the worst of times.”

One final note: a comma is not needed then do not use it.