When to use a semicolon

A semicolon is a punctuation that separates two clauses without using a full stop or a co-ordinating conjunction. For example, look at this sentence below:

Benjamin loves ice-cream; his favourite flavour is cookie dough.

A clause is a part of a sentence. There are two types of clauses-a main clause, and a subordinate clause. A main clause is a part of a sentence that makes sense on its own, for example, look at the same sentence that I have highlighted below:

Benjamin loves ice-cream; his favourite flavour is cookie dough.

In the sentence above, I have highlighted the phrase, ‘Benjamin loves ice-cream’. This part of the sentence gives us a clear idea of the sentence, which helps it make sense. However, the unhighlighted part after the semicolon,

‘his favourite flavour is cookie dough.’, is not a main clause, but rather a subordinate clause. A subordinate clause is part of a sentence that does not make sense on its own. For example, in the above clause, we do not have a clear idea of what happens in the sentence and it is confusing on its own.

This is where a semicolon works. In this case, the semicolon replaces co-ordinating conjunctions that are called the FANBOYS- for, and, nor but, or, yet, so. We can see this is our example sentence by substituting the semicolon with whichever makes sense with the context. In this case, I have highlighted the sentences where the conjunction makes sense, and when it does not.

Benjamin loves ice-cream for his favourite flavour is cookie dough.

Benjamin loves ice-cream and his favourite flavour is cookie dough.

Benjamin loves ice-cream nor his favourite flavour is cookie dough.

Benjamin loves ice-cream but his favourite flavour is cookie dough.

Benjamin loves ice-cream or his favourite flavour is cookie dough.

Benjamin loves ice-cream yet his favourite flavour is cookie dough.

Benjamin loves ice-cream so his favourite flavour is cookie dough.

In this extract, we can see that apart from the conjunction ‘and’, none of the other sentences make sense. This shows that not all FANBOYS are the same, but they serve the same purpose- to join main clauses with a subordinate clause, or to join two main clauses together. However, semicolons also serve another purpose- to replace commas in a list. For example, instead of writing:

I want to visit Tokyo, New York, Sydney and Edinburgh in the future.

You could instead write:

I want to visit Tokyo; New York; Sydney and Edinburgh in the future