Function 1: Breaking up sentence clauses

A comma is needed when you have finished the introductory clause or sentence or are about to start a new one with a conjunction (and, but, so, for, etc.). The comma is the best tool to show where each sentence clause is.

Example 1 – Introductory – When Tommy finished his homework, he yawned and rubbed his eyes

Example 2 – Conjunction – You can stay here and finish your homework or help your father and me with grocery shopping.

Function 2: Creating a series/list

When listing a series of people, objects, places, or ideas in a sentence, the writer should use commas to separate each item; when a list/series is three or more, commas are required.

Example 1: At the market, I bought a blouse, some bananas, a blue vase, and a new baseball cap for my son.

Example 2: She is my loving sister, my responsible babysitter, my closest confidante, and my best friend.

Function 3: To show appositives

An appositive is a phrase used to help identify a less-known or unclear noun, such as a person’s name that you do not know or the name of an organization or anything else. It helps ensure that all readers know precisely what or to whom you are referring. They can occur before or after the sentence’s subject and are separated by commas.

Example 1: Founder and CEO of Facebook, Mark Zuckerberg, is known for his intense love and interest in all things Chinese.

Example 2: Peter Randell, a celebrated local history teacher at Queen Elizabeth School, has decided to retire at the end of this school year.

Function 4: Indicating a personal address or direct quotation

When we are writing dialogue, and someone addresses another person, a comma shows they are addressing that person. In addition, we use commas to set off a direct quotation (but not an indirect quotation).

Example 1 – Address – I think you are right, Stephen.

Example 2 – Direct Quotation – Stephen replied, “Thank you for believing me.”

Example 3 – Indirect Quotation – Stephen said he was thankful that we believed him (*no comma for indirect quotations)

There are, of course, many more uses of the comma, but we hope our initial guide helps learners in these commonly seen scenarios. Learn the conventions and stay consistent, and the quality and readability of your writing are sure to rise with you.

Author: Thomas Longrigg