Skip to main content

The Comma According to Trask

There are only four specific uses for a comma according to R.L. Trask in his Guide to Punctuation: Listing, Joining, Gapping, and Bracketing. If the comma you want to use doesn't fit into any of those categories then the comma is the wrong choice of punctuation. This is my interpretation and summary of Trask's section on commas.

Listing Commas

These are the commas we're most familiar with.

Apples, oranges, grapes, and pears
The serial (or "Oxford") comma (the comma before "and") is not compulsory, but it does help to avoid ambiguity, such as in the infamous example:

I'd like to thank my parents, Ayn Rand and God.
It is only important to be consistent in your choice to use, or not use, the serial comma. If one of your sentences contains an ambiguity that requires a serial comma, you must edit every other sentence that contains a list where the serial comma has been omitted.

Joining Commas

A joining comma joins two sentences together with a connecting word such as and, or, but, while, or yet.

We will wait in the car, but Sarah will return home to pack.
The sentence above would require a semi-colon rather than a comma without the use of the connecting word "but".

Gapping Commas

The gapping comma is used to indicate that (repeated) words have been left out of a sentence.

The Cambridge students decided to play chess; the Oxford students, cricket.
The comma replaces the words "decided to play" in the sentence above.

The gapping comma, like the serial comma, can be omitted if there is no ambiguity caused, and if the use or omission is consistent throughout the document.

Bracketing Commas

If a portion of a sentence can be placed in brackets it can also be placed between commas for clarity. And commas are less intrusive than brackets. Another way to determine whether bracketing commas are required is to read the sentence without the phrase in question. Use commas if the sentence is still complete without the phrase. But again, as with the gapping comma, bracketing commas can be omitted if doing so doesn't affect the clarity of the sentence or cause ambiguity.

Sam initially wanted a coffee, but, after having to walk all the way to the cafe, decided on a cold drink instead.
"after having to walk all the way to the cafe" is extra information that can be removed from the sentence and it will still make sense.

Bracketing commas are always used in pairs, unless the phrase falls at the beginning or end of a sentence. It is better to leave a comma off completely than to use only one of a bracketing pair in the middle of a sentence. A very common error in a sentence like the example above is to omit the first bracketing comma after "but".

Once you wrap your head around the four uses of the comma it becomes much simpler to deal with this most common of punctuation marks.

R. L. Trask was a Professor of Linguistics at the University of Sussex and highly regarded as both a lecturer and the author of books such as Mind the Gaffe! and Say What You Mean : The Superior Person's Guide to Precise and Lucid English Usage. Larry Trask's combined American and British perspective on language usage is particularly useful in our global era. He was born in the United States in 1944, and lived in England from 1970 to his death in 2004.

Elle Carter Neal is a writer based in Melbourne, Australia. Visit her website for more grammar and writing articles. Stay and browse through her resources for writers or follow her writing insights at her Fictional Life Blog.


  1. Elsa
    That makes things so simple- thanks! I'm going to put a link to your post at our Writers Association Blog. I think most writers need to read this.

    Punctuation- Eish!!

  2. Excellent post Emma. Very clear and very useful. Thank you.

  3. Very good, Elsa! I'm keeping the permalink to this post. Never read such a succinct and clear easy to grasp and implement tutorial on correct uses of the comma.

    Nice job.

  4. Thanks for posting this, Elsa. Does make it easier to figure out how to use commas. I still find great disparity between what some writers, editors, and publishers require.

  5. Elsa,

    Where were you when I was memorized 513 different rules???? This is so much simpler. Thank you.


  6. I'm glad it was helpful. I remember the lightbulb going off when I first read Trask's much longer explanation. Reading Marvin's post about commas reminded me about the four uses - in fact Trask begins his entry with "Forget everything you think you know about commas."

    Publishers will still have their own rules when it comes to the optional commas, but at least you know exactly why you're using a comma (or not using one).

  7. This is so helpful. I saved the original post in 2008, but lost it. Glad you re-posted it.

  8. The way I decide on commas is to first say the sentence out loud. If I pause, a comma probably goes there. Of course, that isn't always true so I do think second of the four rules. My drafts always have a lot of commas in them.

  9. Thanks for the advice. As an editor, I sometimes wonder if a comma belongs in certain places and not others. Sometimes it's an easy fix, sometimes not.

  10. I am editing right now so this is a wonderful and relevant refresher for me. Thanks so much for the post!

    Holli Castillo
    Gumbo Justice

  11. Love it, love it, love it! The example of not using the Oxford comma left me laughing hilariously. I've been in an ongoing discussion with others about the value of its use, so this example - which I had not seen before - will help me support my argument in its favor. Adding to that the necessity of consistency, I will rest my case.

    Great post! Thanks for posting it again.

  12. Great refresher, thanks for posting this again, Elsa!

    Though I usually rewrite rather than single out the word "but" between commas like that. Punctuation can serve to highlight desired aspects of our prose, and corralling the word in this example seems an accidental use of this technique on a relatively unimportant word.

  13. I still remember my high school English teacher: "Comma and, comma but, comma for. Commas go around 'extra stuff.'"

    I'm guilty of not making sure I have perfect consistency in serial commas. My first editor (for an e-publisher) said house style guides dictated as FEW commas as possible because back then, there were no dedicated e-readers and people were reading on little tiny PDAs. Commas took up space. And, the CEO would say, "those rules are for formal writing, and we're not writing formal literature."

    So, I had to unlearn old habits and now I'm getting back into the "rules" again.

    My bugaboo was (still is) people who don't understand there are 2 uses for the word "however" and the punctuation makes a difference.

    Terry's Place
    Romance with a Twist--of Mystery

  14. When in doubt, I usually put one in if the sentence is hard to read without one. Might be easier to reconstruct the sentence, but sometimes I happen to like it anyway.

    Morgan Mandel

  15. I also prefer to use commas sparingly so I'm unlikely to use them with a "but" unless the sentence didn't make sense. I am a fan of the Oxford comma, though.

  16. Great post and I agree with a few others - simple, useful. I'm sharing - FB and Twitter - and saving.


Post a Comment

The Blood-Red Pencil is a blog focusing on editing and writing advice. If a glitch is preventing you from commenting, visit our Facebook page and drop your wise words there: Blood-Red Pencil on Facebook