Comma Use in a Series

Learning Objective:

  • Use commas correctly in a series.

Commas(,) A punctuation mark used to group and separate information in sentences. group and separate information in sentencesA group of words, phrases, or clauses that expresses a complete thought. A complete sentence has these characteristics: a capitalized first word, a subject and a predicate, and end punctuation, such as a period (.), question mark (?), or exclamation mark (!).. Their purpose is to help the reader understand what the writer is trying to say. While there are several different ways to use commas, known as the "Comma Rules," this lesson will focus on one of them: using commas in a series.

Writers use commas to separate items in a list or when showing a series of information. Each comma helps the reader to see a break between the items in the list, which helps the reader to keep track of how many items are included. For example:

I need to take my notebook, paper, and pens to class.

In this sentence, you can see that the writer is listing three items he or she needs to take to class and has separated each item with a comma. What would happen if the writer had NOT included commas?

I need to take my notebook paper and pens to class.

Without the commas, the reader may become confused about the meaning of the sentence or what the writer is trying to say. Does the writer need notebook paper or a notebook and paper? It is not clear to the reader that this is a list. This is one reason why using commas in a series is essential to communicating clearly.

Special Note: The traditional rule for using commas in a series is to include a comma between the last two items. Note the comma between paper and and pens in the example:

 I need to take my notebook, paper, and pens to class.

Some writers prefer to leave out the last comma, and this has become an acceptable practice that you will see in many readingsA piece of writing to be read. A reading can either be a full work (i.e., a book) or partial (i.e., a passage).. However, it is an exception to the rule and can sometimes be wrong if the last two items in the series cannot be clearly identified as separate. Using the comma is always correct, so unless you have mastered the use of the comma, it is easier to follow the traditional rule.