Here is another battleground in the world of publishing. Many modern publishers avoid the comma wherever possible. Conversely, others encourage the proper use of commas and abhor the ambiguities that can arise from their incorrect use. The comma has three main functions: to clarify the grammar of a sentence; to avoid ambiguity; and to highlight the rhythm, timbre and inflection of the words.

Here are some general rules for using the comma.

  1. Separating words in a general list:
    • Some common punctuation marks are the comma, apostrophe, full stop and semicolon.
    • We enjoyed a movie, a marvellous meal, some exquisite wine and a walk along the riverbank.
    Note: the general rule here is if you can place the words ‘and’ or ‘or’ between these words, then the comma is correct.
    The serial comma
    There is considerable debate about whether to place a comma before the final ‘and’ in a list:
    The colours of the flag are red, white, and blue.
    This is known as the serial comma (sometimes the Oxford or Harvard comma). It is generally not used in Britain, sometimes used in Australia, and widely used in the USA (except by journalists). Preference should be given to using the serial comma if it makes the sentence easier to understand or avoids ambiguity:
    • Well-known coach companies include Pioneer, Cobb & Co., and Greyhound.
    • I dedicate this book to my parents, Amy Smith, and God. [Unless, of course, Amy and God really are your parents.]
  2. Separating a list of adjectives that modify a noun:
    • It was a clear, hot, cloudless day.
    • He was a tall, well-proportioned, dark-haired man.
    Once again, if the word ‘and’ can be used, then a comma is necessary: it was a clear and hot and cloudless day. Sadly, many publishing houses ignore this usage.
    Note: care must be taken to avoid the comma where no list is intended, and where the adjective works in combination with the noun:
    • The Grand Old Party [doesn’t mean the Grand and Old Party].
    • Great German beers [doesn’t mean great and German beers].
  3. Joining two independent clauses connected by a conjunction (and, but, or, while, yet, etc.):
    • Everyone watched the movie, but none enjoyed it.
    • I am appalled by reality TV, yet I can’t help watching Australian Idol.
    • Note: care must be taken if the conjunction is dropped: “Everyone watched the movie, none of them enjoyed it.” This is ungrammatical, and is known as the ‘comma splice’. If, however, the comma is left out, it is known as a ‘run-on sentence’: “Everyone watched the movie none of them enjoyed it.” This error can be fixed in a number of ways:
      • Everyone watched the movie, but none of them enjoyed it. [Use a conjunction after a comma.]
      • Everyone watched the movie; none of them enjoyed it. [Use a semicolon.]
      • Everyone watched the movie – none of them enjoyed it. [An en-dash is a good alternative.]
      • Everyone watched the movie. None of them enjoyed it. [Break the sentence in two.]
  4. To open direct speech:
    • The foreman said, “You will all need to work harder.”
    • The union organiser thundered, “We will not put up with this!”
    Note: there is a growing movement to use the colon with direct speech: The Premier said: “We must improve our infrastructure.” However, consideration should be given to using the comma where you require the reader to take a slight breath before reading on.
  5. To set off interjections, common starter words, and introductory phrases:
    • Stop, or you’ll break something!
    • However, I can’t stop you making a fool of yourself.
    • Yes, that was the book I spoke about.
    • To get a seat, you’ll need to arrive early.
    • When the sun goes down, we’ll take a short walk.
  6. To set off names being addressed, or where ‘unique’ persons or things are introduced by an identifier:
    • I’m asking you, Jemima, please be seated. [I’m addressing her directly.]
    • I asked Jemima to be seated. [No commas here.]
    • My son, John, studies history. [If I only have one son (he’s unique).]
    • But: My son John studies history. [If you have more than one son.]
    Note: Where an identifier describes a unique person or thing (the only one in the world), then use commas. This can be tested by asking whether the identifier makes sense in the sentence by itself. If it does, then the name is non-essential and set off with commas – otherwise, no commas:
    • I went to see the movie Gran Torino with my friend Jemima. [No commas: Gran Torino is not the only movie in the world, and I have other friends besides Jemima. If the names were left out, the sentence would be meaningless.]
    • I went to see Clint Eastwood’s latest movie, Gran Torino, with my best friend, Jemima. [Here, Gran Torino is Clint Eastwood’s only ‘latest’ movie, and Jemima is uniquely identified as my ‘best’ friend.]
      Note: There is an exception to the only-one-in-the-world rule. If the identifier/description of a non-essential (i.e. not unique) name is preceded by an indefinite article (a, an), then use a comma:
      • An Olympic athelete, George Smith, has been injured.
      • But: The Olympic athlete George Smith has been injured.
      • A front-row forward, Jim Jones, scored the winning try.
      • But: The front-row forward Jim Jones scored the winning try.
  7. To set off a weak interjection within a sentence:
    • All players, of course, are expected to obey the rules.
    • My mother, who always read, preferred non-fiction books.
    • Editors, who are in short demand, are required to know the rules of grammar.
    Note: in the examples above, the words between the commas can be removed without affecting the grammatical sense of the sentence. This usage is also a common function of the en- and em-dashes, though generally only where the writer requires the reader to focus more on the interjection.
  8. To avoid ambiguity:
    Take this notice: NO DOGS PLEASE
    Well, I beg to differ – my dog pleases me very much! Of course, the sign is meant to say: NO DOGS, PLEASE. By missing the comma, we have an immediate ambiguity. So, the writer must always be aware that a missing or misplaced comma can cause confusion. Here are some other examples:
    • A woman, without her man, is nothing. [Women need men.]
    • A woman: without her, man is nothing. [Men need women.]
    • Don’t stop! [Please do not stop.]
    • Don’t, stop! [Please do stop.]
    • While Dad was cooking the baby wandered away. [I hope he remembered the salt!]
    • While Dad was cooking, the baby wandered away. [Whew!]
    • “Let’s eat Grandpa!” Jemima said. [Egads! Perish the thought!]
    • “Let’s eat, Grandpa!” Jemima said. [What a relief!]
    • He was only pretending to please her. [The cad!]
    • He was only pretending, to please her. [What a thoughtful man.]

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