1. How to Use a Colon
A colon has one main job: it introduces a specific example or explanation. For example:
- He had one problem: there was no way to get there in time.
In this case, we mention a problem in the first part of the sentence, then we explain exactly what the problem is in the second part of the sentence, after the colon.
- There’s just one rule here: do everything I tell you.
Again, we mention something general in the first part of the sentence (one rule), and then give a specific explanation in the second part, after the colon (what the rule is).
You can also use a colon in this way to introduce a list:
- We’ve invited a small number of people: Bill, Emma, Rachel…
- Tolstoy wrote several books other than War and Peace: Anna Karenina, The Cossacks, Resurrection…
Another use of the colon is to introduce what someone said, if the speech is in quotation marks (“”):
- He said: “Don’t talk to me about this again.”
- They shouted: “Be careful—don’t get too close to the edge!”
In these cases, it’s also possible to use a comma. You can choose which to use—it’s generally a question of style.
After a colon, it’s possible to use a small letter or a capital letter.
If you use a colon to introduce what someone said, you should use a capital letter.
If you use a colon to introduce an example or an explanation, you can choose.
Using a capital letter is more common in American English, while in UK English we almost always use a small letter.
2. When NOT to Use a Colon
We said that a colon has one main job (introducing specific examples or explanations), and one possible use (introducing what someone said).
It’s also important to know when not to use a colon. Here are some common mistakes which English learners sometimes make with colons:
Dear John: Dear John, –> Don’t use a colon at the beginning of a letter or email; use a comma.
Monthly Report January: Monthly Report January –> Don’t use a comma after a title or heading. Generally, you don’t need to use any punctuation after a title or heading.
3. How to Use a Semicolon
Like a colon, a semicolon has one main use: we use it to show a connection between two complete sentences. A semicolon is similar to a full stop.
A semicolon is used instead of a full stop because the writer wants to show that two ideas are more closely connected. It’s generally the writer’s choice whether to use a full stop or a semicolon.
- The population of Shanghai is around 24 million; Beijing has around 22 million people.
- We knew he was guilty; there was no evidence, however.
In both of these sentences, you can see that:
- The two sentences joined with a semicolon are both full sentences. In each case, we could choose to separate the sentences with a full stop.
- The two sentences joined with a semicolon are related, in that they are talking about a similar subject.
4. How to Use Connecting Words with Colons and Semicolons
Often, when we want to join two sentences in English, we use a connecting word like and, but or therefore.
When you join two sentences using a semicolon, you don’t need to use a connecting word. However, if you use a connecting word to join two sentences, you sometimes need to use a semicolon and sometimes a comma. It depends what the connecting word is.
- To join two sentences using and, or, but, yet or while, you should use a comma.
- To join two sentences using however, therefore, nevertheless or meanwhile, you should use a semicolon.
There are other connecting words which require a comma or a semicolon; however, these are the most common.
- The population of Shanghai is around 24 million; Beijing has around 22 million people. –> There is no connecting word, so we use a semicolon.
- The population of Shanghai is around 24 million, while Beijing has around 22 million people. –> We use while as a connecting word, so a comma is necessary.
- The population of Shanghai is around 24 million; however Beijing is slightly smaller, with around 22 million people. –> We use however as a connecting word, so a semicolon is necessary. A full stop would also be possible.
5. How to Use Semicolons in Lists
Semicolons have one other use: they can be used in lists when the items on the lists contain commas.
Usually, when we make a list, we use commas to separate the items on the list:
- We need milk, eggs, sugar and flour.
But, if the items on the list are not just words, but phrases which include commas, we use semicolons to separate the items on the list:
- We travelled to four cities: Santa Fe, which is in New Mexico; Denver, Colorado; Las Vegas, Nevada; and finally Los Angeles in California.
Learn more vacation vocabulary with this Oxford Online English lesson: Talking About Your Vacation.
In this case, because the items on the list are phrases which contain commas, it would not be clear if we also used commas to separate the list items, so we use semicolons instead.
- Only three people showed up: Tom, the head of accounting; Maria, who works in the sales department; and Ellie, who is doing an internship here.
Both the colon and the semicolon are used to show a connection between two ideas, but they operate in a very different way. Let’s finish by comparing the colon and the semicolon directly.
- We have a problem. He isn’t doing enough to help me.
- We have a problem; he isn’t doing enough to help me.
- We have a problem: he isn’t doing enough to help me.
In the first example, we use a full stop. This means that the two ideas aren’t necessarily connected. The problem we have and what he is or isn’t doing could be two completely separate things.
In the second example, we use a semicolon. This shows that the two ideas are connected. We have a problem, AND he isn’t doing enough to help me. So, in fact, I have two problems: the original problem and his attitude.
In the third example, we use a colon. This shows that his attitude/behaviour IS the problem. We can rewrite the second and third sentences to make this clearer:
- We have a problem; he isn’t doing enough to help me. –> We have a problem, and he isn’t doing enough to help me with this problem.
- We have a problem: he isn’t doing enough to help me. –> We have a problem, which is that he isn’t doing enough to help me.
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