This image is from one of Dr. Bailey's books: The Practical Writer (7th edition) Colon

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The colon is an easy mark to use. It typically comes after a complete sentence. This section shows you two common ways professionals use the colon—you should learn these ways, too!

Visual summary

Visual summary of rules for the colon

Rule 1: Use a colon after a complete sentence to point to a word or a phrase you wish to emphasize.


Our new computers have one big advantage: speed.

What's the difference between that sentence and this one?

One big advantage of our new computers is speed.

The difference is emphasis, isn't it? The first sentence really puts a spotlight on the word speed. What's the better sentence? We can't say: it depends on how much you want to emphasize that word. But the better writer can probably do it both ways.

Rule 2: Use a colon after a complete sentence to point to another closely related sentence.


Our new computers will be popular: they're much faster than our old ones.

Instead of using a colon, you could put a period after the word popular, couldn't you? The period would certainly be correct.

But remember that anything can come after a period. The writer might continue the thought or switch to anything else. The period doesn't do much to tell the reader what's coming up. But the colon says, "Here comes some more about what I just said."

In other words, in this case, the colon is a more precise signal to the reader than a period would be.

Frequently asked questions about the the colon

How much space should you put after a colon?

When should you capitalize after a colon?

What's a common misuse of the colon?

Does a colon always come after a complete sentence?

Want to see samples of good sentences with a colon?

Next step

Now let's turn to the dash.

Copyright 2007 by Edward P. Bailey
(all rights reserved)