The Complicated World of Commas


First of all, I want to say Happy Canada Day to all my Canadian readers! I hope the weather where you are is as nice as it is here in the nation’s capital.

And now, dear readers, the moment I know some of you have been waiting for. Today we are going to talk about commas.

Unlike other types of punctuation, the comma is the most versatile, which is perhaps what causes the anxiety some people feel about using commas correctly. In addition, not all grammarians agree on certain uses of the comma, such as the serial comma, which can further add to the confusion. Today, I will attempt to bring a little clarity to this subject. So let’s get started!

The most important thing to remember about the comma is that it’s used to indicate the smallest break in a sentence, which translates into a slight pause when read aloud. (You can contrast this with the longer pauses indicated by a semicolon or a period.) Here are a few rules to help you out:

Separating Elements

A comma can be used to denote an element in a sentence, which includes individual nouns and adjectives, appositives, and descriptive phrases. When used in this manner, you should place one comma on either side of the element, like so:

  • The sign said we had just entered Transylvania, Saskatchewan.
  • Igor, who was a strange little man, answered the door.

Likewise, if you are listing items in a series or using two or more adjectives before a noun, you should separate those items with commas, as in the following examples:

  • The doctor asked us to bring a staple gun, sutures, bubble gum, and jumper cables.
  • Frankenstein’s lab was dark, musty, and littered with limbs.

A serial comma, or Oxford comma, is when you place a comma before the conjunction joining the last two items in a series of three or more elements. Some people frown about this use, but the idea behind a serial comma is to remove any ambiguity. Check out both versions of the following example:

  • The doctor had invited Gertrude, Marcus, Helga, his mother and his ex-wife.
  • The doctor had invited Gertrude, Marcus, Helga, his mother, and his ex-wife.

Note how the serial comma clarifies the meaning. In the first example, it kind of sounds like Helga is the doctor’s mother and also his ex-wife. In the second example, it’s much clearer that those are actually three different people.

Which and That

Which and that is probably a whole other post, but this often trips people up, so let’s look at it briefly. The word that is often used to introduce a restrictive relative clause, which contains information that is essential to the sentence. Restrictive clauses never require a comma. On the other hand, the word which is often used to introduce a non-restrictive relative clause, which could be left out without affecting the sentence. Non-restrictive clauses do require a comma. Here are examples of each:

  • The brain that Igor placed in the monster’s head was the final step.
  • The experiment, which had cost Frankenstein dearly, was a success!

Independent and Dependent Clauses

Commas are generally used to separate independent clauses that are connected by a conjunction. (If the clauses are very short, it’s okay to leave out the comma.)

  • The lights in the castle flickered wildly, and the monster sat up.

In dependent clauses, a comma should be used when the dependent clause comes before the main clause. However, if the dependent clause follows the main clause, a comma is not used. See the following examples:

  • When the monster broke free from his restraints, Frankenstein’s audience began to scream.
  • Frankenstein’s audience began to scream when the monster broke free from his restraints.

Exclamations, Introductions and Direct Addresses

Commas are also used to set off words that are exclamatory (Oh, crap!), introductory (Well then, we’d better fetch our pitchforks.), or in direct addresses (Dr. Frankenstein, your cadaver has gone AWOL.).

And that, dear readers, is an overview of the comma. If you still find yourself confused about when and where to place a comma, my suggestion is to read the sentence out loud. Where did you pause naturally? That’s probably where the comma should go.


Image credit: chrisharvey /


7 thoughts on “The Complicated World of Commas

  1. Thank you, Suzanne, for taking the time to write this for us. For me, commas are like learning a new language. This helped a lot. In fact, I intend to bookmark it so I can refer to it when necessary. Please let me know if I’ve punctuated this comment correctly. I’m guessing I left out at least one comma, or inserted one too many. 🙂

    1. You’re very welcome Steph! I’m glad you found this post useful. And you did a fantastic job with your punctuation — I wouldn’t change a thing. 🙂

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