To me, part of the beauty of a comma is that it offers a rest, like one in music: a break that gives the whole piece of music greater shape, deeper harmony. It allows us to catch our breath (Pico Iyer).

This post gives the comma its due regard and highlights its functions so that we can judiciously remove it, honour its placement, or insert it where it has its rightful place.

Primary functions of the comma 

Separator

As a separator, the comma is used to separate items in a list, adjectives of the same type (qualitative or classifying), introductory words and phrases, such as although or however, and words or phrases in apposition (for example, Ms Dlamini, the copy editor).

Parentheses

To function as parentheses, commas can be used on either side of a non-defining clause (a clause or phrase that can be removed without changing the meaning of the sentence) or to separate a section of a complex sentence to make it easier to read. For example: She walked slowly to the shop, her backpack weighing heavily on her shoulders, to buy the bread her mother needed, absorb the fresh air, and think through what she might say once home.

Direct speech

A comma introduces or ends direct speech: She said, ‘This blog post needs work.’

‘I rather like it,’ he retorted.

Common cases of incorrect comma use 

Using a comma splice

A comma splice happens when two complete sentences or main clauses are separated by a comma instead of a full stop.

• Incorrect: My father sat on his chair, he drank his coffee slowly but with sheer delight.
• Correct: My father sat on his chair. He drank his coffee slowly but with sheer delight.

Using a single comma for non-defining clauses

First, we need to recognise whether the clause is defining or non-defining. Defining clauses require no commas, but non-defining clauses always need two commas.

• Incorrect: My teacher, who had always been strict at school seemed kinder when I met her socially.
• Correct: My teacher, who had always been strict at school, seemed kinder when I met her socially.

Using a comma before an adverbial phrase or to link adverbs

Many people incorrectly use commas to link adverbs or before an adverbial phrase, such as however, as a result or therefore.

• Incorrect: I like to eat biscuits regularly, however, my body weight remains constant.
• Correct: I like to eat biscuits regularly. However, my body weight remains constant. (Rather use a semi-colon or a full stop to separate the preceding clause.)

The serial comma 

A discussion about the comma could never be complete without some reference to the serial comma, otherwise known as the Oxford comma. The serial comma is the comma used before and or or in a list. If a style requirement states that the serial comma is to be used, then it is imperative to use it consistently. For example: We ate grapes, berries, apples, and carrots. They did not enjoy preparing food, participating in the scheduled activities, or attempting to engage any unfamiliar people.

A concluding comment 

Martin Cutts (2013) cautions us to be sparing with commas but to ignore the advice often heard on writing courses to use a maximum of one comma per sentence, claiming, It’s just plain silly. And Lynne Truss (2009) offers this closing thought: No wonder feelings run high about the comma. When it comes to improving the clarity of a sentence, you can nearly always argue that one should go in; you can nearly always argue that one should come out.

Clearly this punctuation mark has attracted followers and critics from far and wide. This post has only touched on the correct use of the comma and how to identify its incorrect use; the sources listed below have a lot more to say on the matter.

References:

Butcher J, Drake C & Leach M 2006 (4th ed) Butcher’s copy-editing: The Cambridge handbook for editors, copy-editors and proofreaders. Cambridge: Cambridge University Press.

Cutts, M 2013 Oxford guide to plain English (4th ed). New York: OUP.

Linnegar J & McGillivray K 2019 Grammar, punctuation and all that jazz … Milnerton: MLA Publications.

New Oxford style manual 2016 New York: Oxford University Press.

Seely, J 2007 Oxford A-Z of grammar & punctuation. New York: OUP.

Steynberg, M 2018 The PEG guide to grammar and punctuation. Professional Editors’ Guild.

Truss, L 2009 Eats, shoots & leaves: The zero tolerance approach to punctuation. London: Harper Collins.