英语语法：117 Colons

Grammar Girl here.

Today's topic is how to use colons 2.

Sallie in Detroit Lakes, Minnesota, and a listener named Mike wondered when to use a colon 1 and when to capitalize the first word after a colon.  One of my favorite grammar books, titled* Punctuate 3 It Right, has a wonderful name for the colon: the author calls it the mark of expectation or addition (1). That's because the colon signals that what comes next is directly related to the previous sentence.

The most important thing to remember about colons is that you only use them after statements that are complete sentences. Never use a colon after a sentence fragment.

For example, it's correct to say, "Grammar Girl has two favorite Thanksgiving dishes: green-bean casserole and stuffing." That's correct because "Grammar Girl has two favorite Thanksgiving dishes" is a complete sentence all by itself.

Notice how the items after the colon expand on or clarify what came before the colon. I referred to my favorite dishes before the colon and then specifically named them after the colon. A quick and dirty way to decide whether a colon is acceptable is to test whether you can replace it with the word namely. For example, you could say, "Grammar Girl has two favorite Thanksgiving dishes, namely, green-bean casserole, and stuffing." Most of the time, if you can replace a colon with the word namely, then the colon is the right choice.

Let's go back to the complete-sentence issue: it would be wrong to say, "Grammar Girl's favorite Thanksgiving dishes are: rolls and cranberry 4 sauce" because "Grammar Girl's favorite Thanksgiving dishes are" is not a complete sentence by itself (and because those aren't my favorite dishes). You can often fix that problem by adding the words the following after your sentence fragment. For example, it would be fine to say, "Grammar Girl's favorite Thanksgiving dishes are the following: green-bean casserole and stuffing" because you've made the thing before the colon a complete sentence by adding the words the following.

For some reason, people seem to get especially confused about when to use colons when they are introducing lists, and Mike specifically asked about using colons before lists, but the good news is that the rules are the same whether you are writing lists or sentences: you use a colon when you could use the word namely and after something that could be a complete sentence on its own.

Finally, everyone always wants to know whether they should capitalize the first word after a colon. The answer is that it's a style issue, and it depends on what is following the colon. Although the most conservative grammarians would say that you should capitalize the first word after a colon when the colon introduces a complete sentence, there are a lot of grammarians who say that it isn't necessary. Since you never capitalize the first word after a colon if it is introducing something that isn't a complete sentence, I find it easier to adopt the less conservative rule for introducing complete sentences, and then all I have to remember is that the first word after a colon is always in lowercase (unless, of course, it is a proper name or something else that's always capitalized). But if you are writing for someone who uses a style guide, you should check to see if they have a preference because it is a style issue.

So those are the rules about colons for today: use a colon when you could use the word namely, only use a colon after a complete sentence, and don't capitalize the first word after a colon.

That's all. As always, this is Grammar Girl. I'm very excited today because I have a book giveaway! An author named Mark Phillips publishes grammar and vocabulary books, and he was kind enough to send me copies so that I can give them away to listeners. So, this is the first official Grammar Girl book giveaway! The book is titled Tarzan and Jane's Guide to Grammar, I randomly 5 picked a name out of the e-mails I have from people who have contacted me or made a donation, and Donna H. is the winner. So Donna, I hope you enjoy Tarzan and Jane's Guide to Grammar! For everyone else, I will also have other books to give away in the next three episodes! Thanks again to the author, Mark Phillips, for providing the books.

I can be reached by e-mail at..... and voice-mail at 206-338-GIRL (4475).

Thank you for listening.