More on Commas

(c) Introductory elements

Some sentences begin with a little introduction. Here’s an example:

‘After eating her dinner, the greyhound went to sleep.’

You’ll see that the introduction (After eating her dinner) is separated by a comma from the rest of the sentence. In general, use a comma to separate the introductory elements of a sentence from the main clause. For example:

•       ‘When the rain had stopped, we went out.’

•       ‘After having a shower and a shave, he dressed himself with his usual care.’

In the above sentences, missing out the comma would be confusing and another highly visible error for your readers.

If the introduction is very short (three words or less), you can leave out the comma:

•       ‘As a result he decided not to come.’

•       ‘After his shower he got dressed.’

(d) Parenthetical elements

A parenthetical element (or aside) is a part of the sentence that could be left out without altering the essential meaning of the main sentence. Use a pair of commas to separate parenthetical elements.

Here, the parenthetical element is the famous Italian poet:

•       ‘Dante, the famous Italian poet, was born in Florence in 1265.’

A common mistake (I see it time and again) is to leave out the second comma (in this case, after poet). Remember the rule of two!

(e) Restrictive and non-restrictive clauses, words and phrases

Things get a little more complicated when you have restrictive and non-restrictive clauses. What are these exactly?

A restrictive clause, word or phrase gives us information that clarifies a previous element and is essential to the meaning of the sentence. For example:

•       ‘The boy who lives next door is a friend of mine.’

A non-restrictive clause, word or phrase adds extra information that is not essential to the meaning of the sentence. For example:

•       ‘The boy, who lives next door, often goes to work on a bicycle.’

See the difference?

In general, commas should be used before and after non-restrictive clauses and phrases, and omitted around restrictive clauses and phrases.

(f) Appositives

These are words or phrases that define or identify the noun or phrase that comes before them. This sounds complicated, but when you see the examples below you’ll find it’s really quite simple.

When an appositive is essential to the meaning of the noun it belongs to, don’t use commas. When the noun preceding it is enough on its own, use commas.

Here’s where commas are needed:

•       ‘My sister, Sue, is a paramedic.’  

         [I only have one sister, whose name is Sue; her name isn’t essential to the meaning of this sentence]

And here’s where commas are not needed:

•       ‘My sister Sue is a paramedic.’

         [Sue is just one of my sisters; her name is needed to identify her as the paramedic]

You can see the difference two little commas make!

(g) No comma between subject and verb

Don’t use a comma between the subject and the verb, even when the subject is complex:

‘The curious clanging sound that came from the cupboard left him wondering about his sanity.’

Although the subject of this sentence is complicated (‘The curious clanging sound that came from the cupboard’), the meaning is perfectly clear without commas; adding a comma after ‘cupboard’ and before ‘left’ would be a highly visible error.

Summary

Using too many commas is just as bad as using too few.

It isn’t correct to think commas need to be used whenever there is a natural pause in speech.

Leave out commas if their omission doesn’t affect the meaning of the sentence.