A semicolon does two main jobs: it joins two complete sentences that belong closely together, and it separates the items of a list when the items already contain commas. It marks a stronger break than a comma and a weaker one than a period.
The semicolon seems to be one of the most feared punctuation marks, because it looks hard to use. Is it a period? Is it a comma? A mixture of both? Neither?
The answer is a mix of both. Like a comma, the semicolon marks a pause between two clauses, but the pause is shorter than the one a period makes at the end of a sentence.
However, do not confuse a semicolon with a colon. The two cannot be used interchangeably:
- Correct: Here's what we'll do: first the attic, then the basement.
- Incorrect: Here's what we'll do; first the attic, then the basement.
Using the semicolon
Joining two sentences
The basic function of a semicolon is to link two independent clauses, that is, two sentences that could stand on their own, without the longer pause a period would create. It also lets you leave out a conjunction such as and or but. Compare:
My wife wants to go to Hawaii for the holidays. I'd prefer France.
My wife wants to go to Hawaii for the holidays; I'd prefer France.
The semicolon narrows the gap between the two clauses. A writer may want that for emphasis, or for the way the text flows when it is read.
Separating list items that contain commas
A semicolon also separates the items of a list when the items are already divided by commas. This way, the reader can see which parts belong together:
The following people are nominated for the award: Markus, USA; Jerome, France; Justin, South Africa; Antonio, Italy.
In dialogue
One use of the semicolon is especially interesting if you write fiction. In a story or a novel, your characters talk, and what they say is often interrupted by a speech tag or a description. In older fiction, you will often see a semicolon after the tag when the two parts of the speech are closely linked:
"I don't know what to do anymore," Alexa said; "this situation just keeps getting worse."
Today most writers use a period there and start the second part as a new sentence:
"I don't know what to do anymore," Alexa said. "This situation just keeps getting worse."
Before however, therefore, and similar words
When a word or phrase such as however, therefore, of course, for example, or thus links two complete sentences, put a semicolon before it and a comma after it:
We can go to the beach later; however, I think the weather will change soon.
A comma alone in that place is a common mistake called a comma splice. We can go to the beach later, however, I think the weather will change soon is wrong. A period works, though, if you prefer two sentences. To learn more about these linking words, read how to use conjunctive adverbs.
When not to use a semicolon
As stated above, never use a semicolon in place of a colon. A colon introduces a list, a long quotation, or a sentence that explains, expands, or illustrates the first one. In those cases a semicolon is wrong. All you need to know about the colon covers its uses in detail.
Also, do not use a semicolon together with a conjunction such as and, but, or, nor, for, yet, or so. Use a comma instead:
This cake looks delicious, but I really shouldn't eat it.
The only exception is a sentence whose first clause already contains a comma. There, a semicolon before the conjunction shows the main break more clearly:
I don't think that Sally knows what she's doing, if she ever does; but we have no choice but to trust her with this.
If you are still unsure about a semicolon, the Spell Checker checks punctuation as well as spelling and grammar.