What Is A Colon And How Do You Use It?

What is a colon?

A colon is a punctuation mark used to introduce lists, quotes, or further explanation. It is also used to separate items in non-grammatical structures.

How to use a colon

Knowing how to use a colon correctly can be tricky, especially when style guides such as the Chicago Manual of Style, disagree. To master the subject of colons, you’ll need to know the basic rules for using them as well as what distinguishes them from semicolons and comma. Read on.

To join two sentences

A colon is frequently used to join two independent clauses, or a group of words that contains a subject and a verb, and can stand on its own as a complete sentence. For example, when an explanation takes the form of a second independent clause that follows a main independent clause, you can join the two clauses with a colon. Here is an example: “Jenny had an idea: she would pick up a cake on her way to her friend’s house.” Both the clause before the colon and the one after it are complete sentences. The clause after the colon further explains Jenny’s idea.

To introduce a quote

Similarly, a colon may introduce a quote that comes after an independent clause. For example, “Bob seemed to like that idea:‘Yeah, let’s do that!'” In this sentence, the words before the colon could stand alone as a complete sentence. The colon emphasizes the coming quote.

To introduce items in a serial list

A colon can be used to introduce a list. In general, the portion of sentence before the colon should be a complete sentence (it should contain a subject and a verb). Phrases like the following may sometimes be used to signal an introduction to a list. For example, “Here’s a list of groceries I need: a loaf of bread, a quart of milk, and a stick of butter.” The words preceding the colon stand as a complete, grammatically correct sentence. The list offers further explanation.

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To express time

Of course, you may not realize it but you see the colon practically every day—when it’s used to express time. A colon separates the minutes from the hours, like so: “It is 7:30 pm, and I need to go home.”

Do you capitalize after a colon?

Like so many grammar questions, the answer to this one depends on the style guide you’re using. For the most part, however, you do not need to capitalize after a colon. You do not need to capitalize after a colon if what follows the colon is a list:

  • I think Albert only knows how to cook three things: toast, scrambled eggs, and spaghetti.

If what follows the colon is a complete sentence, some style guides (such as the American Psychological Association’s) do recommend capitalizing the word that follows the colon.

  • It snowed all morning: The roads were impassable by 8 am.

How does a colon differ from a semicolon and comma?

These uses of the colon shouldn’t be confused with the uses of the comma or semicolon. Allow the meaning of the sentence to help guide the decision to use a colon, comma, or a semicolon in a sentence.

Colon vs. semicolon

Both a semicolon and colon link independent clauses together, so you may be confused about when to use which.

Unless the second independent clause explains the first, a semicolon is sufficient to join two closely related independent clauses. For example, Lincoln was first elected to the Presidency in 1860; Kennedy was first elected in 1960.

Colon vs. comma

The difference between a comma and a colon (:) is even more pronounced. A list that isn’t introduced by a clause or doesn’t offer further explanation doesn’t need punctuation before it. For instance, “I need to visit the butcher, the baker, and the candlestick maker.”

A colon can be used to introduce a list—but you’ll still need commas to separate the items in the list. For example, Here’s a list of groceries I need: a loaf of bread, a quart of milk, and a stick of butter.

What are the non-grammatical uses of a colon?

Colons have a variety of non-grammatical uses. Titles and subtitles are separated by colons, as in William Shakespeare: The Complete Works. Colons are also found in times (12:30 pm), in ratios (10:1), in Biblical references to a chapter and verse (John 3:16), and in the salutations of business letters (Dear Mr. President:).