Colons—How in the world do you use those?

If I could have it my way, three punctuation marks would have permanent how-to guides hovering above them.

Colons, semicolon, and dashes.

Ever felt that way yourself? Well, over the next three weeks we’ll do the best we can—in the absence of hovering how-to guides—to lay out their uses as simply as possible.

First up: colons. Apart from their uses in expressing time, chapters and verses, and ratios (all of which I’m sure you know already), they’ve got two other uses that we’ll consider.

Use number one

For this first use, I like to think of colons as directing the reader to information that fulfils a promise just made. Take the following sentence:

He read three classic novels last month.

If we think of that sentence as promising the titles of those novels, we’ll see what I mean:

He read three classic novels last month: Pride and Prejudice, Anna Karenina, and Oliver Twist.

Here’s another sentence that promises something:

He’d spent his whole life striving for something that seemed perpetually just beyond reach.

Now insert Mr Colon:

He’d spent his whole life striving for something that seemed perpetually just beyond reach: love.

Here’s one (almost) final example:

I could tell it all from the look in his eyes.

And enter Mr Colon:

I could tell it all from the look in his eyes: he was a man crushed by disappointment.

In all these examples, what comes after the colon fulfils the promise of what came before the colon.

Before we move on, though, there’s something we need to notice: colons always follow complete sentences. (See how I sneakily gave you another colon example there!) The following, for example, is wrong:

For the camping trip we need: tents, sleeping bags, and torches.

That colon shouldn’t be there because “For the camping trip we need” isn’t a complete sentence. A colon is used to add extra information to the end of a complete sentence. When a list of items is simply part of the sentence itself, that’s exactly the way it should be left:

For the camping trip we need tents, sleeping bags, and torches.

If we wanted to write this sentence with a colon, we’d write it like this:

For the camping trip we need three things: tents, sleeping bags, and torches.

The first sentence promises “three things”; after the colon, we fulfil that promise. (By the way, next week I’ll explain why on earth I used a semicolon there! 🙂 )

Use number two

For this second colon use, let’s think of colons as directing the reader to a second sentence that explains or justifies the first. Take the following examples:

Winter is my favourite season: I love the snow and ice.

Hawaii has a great amount of rainfall: its mountains act like rain-cloud magnets.

Movies are really expensive to make: hundreds of skilled people must be paid.

The second sentence in each pair provides a reason, a validation, for the statement made in the first sentence. Therefore, for example, the next sentence would be incorrect:

I’ve flown hundreds of times: he’s only flown a few times.

What does the second statement do to justify the first? Nothing! No, in that sentence we’d need a semicolon, but semicolons are our topic for next week. But before I go and start writing that  …

There are two things we should mention.

First, you may have sometimes seen a capital letter after a colon.

Movies are really expensive to make: Hundreds of skilled people must be paid.

The key here is whether or not a complete sentence follows the colon. If it’s not a complete sentence, a capital letter should not be used (unless it’s a name). If it is a complete sentence, a capital letter is optional. In British English, it is typically not used. In American English, it is often used, but it is still optional.

Second, you may have wondered why anyone bothers with colons when full-stops (periods) seem to work fine.

Movies are really expensive to make. Hundreds of skilled people must be paid.

The reason for the colon lies in the relationship between those two statements. With the full-stop (period), those are two separate statements, and any relationship between them must be assumed by the reader. With a colon, the writer can make the relationship clear: the second statement specifically justifies, explains, or fulfils the first.

Let’s summarise

Colons have two uses. First, colons direct the reader to information that fulfils a promise just made:

Although I wish I didn’t have to, there’s something I need to say: this blog is almost over.

Second, colons direct the reader to a second sentence that explains or justifies the first:

Concorde was the fastest passenger jet ever built: it flew at over twice the speed of sound.

Until next time—when semicolons demand an explanation—have a great week!

And for lots more punctuation pointers, check out My Big Blog Directory.

But if you’d like some entertainment instead, take a look at Glimpses—my free book of short stories.