You have a list ready for your school newspaper story, but the punctuation before it looks uncertain. Should you put two dots after the verb? To use a colon within a sentence, first check the words before it, then decide how the material after it relates to them. The colon as punctuation introduces information that completes, explains, or illustrates a preceding complete thought.
Punctuation, Colon: Test the Words Before It
What is a colon punctuation mark used for? It points forward to something that develops the thought immediately before it. Think of this punctuation mark as a small sign saying “here is what I mean.” In ordinary prose, the words before that sign should form an independent clause: a group with a subject and verb that can stand alone as a sentence.
Try covering everything after the mark. In “The reporter packed three things: a notebook, a recorder, and a pen,” the words “The reporter packed three things” can stand alone. The list identifies those three things. This test makes placing a colon in a sentence much easier: check for a complete thought before checking the list.
In punctuation, colon placement depends on the relationship between the two sides. The material after the mark can be a list, a phrase, or a complete sentence. It does not have to stand alone, but it should fulfill the expectation created by the first clause. Purdue OWL’s punctuation overview describes these uses and compares the colon with other marks.
Introduce a List Without Breaking the Sentence
A colon before a list works when the opening clause already makes sense on its own. Here is an example from an imaginary newsroom: “The editor assigned three jobs: checking names, confirming dates, and reviewing captions.” The first part is complete, and the items specify the jobs.
Now consider the broken version: “The editor assigned: checking names, confirming dates, and reviewing captions.” Here the verb “assigned” leads directly to its objects; the colon interrupts that connection. Remove it: “The editor assigned checking names, confirming dates, and reviewing captions.” Alternatively, add a complete opening clause, as in the first version.
The same issue appears after a preposition. “The reporter spoke with: students, teachers, and parents” leaves “with” waiting for its object. Write “The reporter spoke with students, teachers, and parents,” or use a complete clause: “The reporter spoke with three groups: students, teachers, and parents.” A list can be perfectly clear without a colon. This punctuation mark is a choice, not an entrance ticket for every series.
Add an Explanation or a Related Clause
You can also use a colon in a sentence to introduce one explanation rather than several items: “The interview had one recurring problem: unclear questions.” The phrase after the mark names the problem. It completes the promise made before it.
A full sentence may follow too: “The photographer had a good reason to return: the afternoon light revealed details hidden in the morning.” The second clause explains the reason. Because both sides have a subject and a verb and can stand alone, each is an independent clause. The colon makes their particular relationship clear: the second supplies the reason announced in the first.
Capitalization is one detail of colon punctuation that varies by style guide. In American English, some guides capitalize a complete sentence after it while others prefer lowercase in certain cases. Follow your publication’s rule, and always capitalize proper nouns. In punctuation, colon conventions can also vary in formal quotations and display text, so check the relevant house style when those arise.
Compare Other Marks
A semicolon can join two closely related independent clauses without announcing that the second explains the first: “The editor checked the spelling; the photographer reviewed the captions.” Each side could stand alone, and neither is presented as the explanation of the other. Purdue’s guide to commas and semicolons offers more examples of this connection.
An em dash can introduce an emphatic addition in a less formal voice: “The reporter needed one thing—time.” A colon gives the introduction a more deliberate, orderly feel: “The reporter needed one thing: time.” Both versions point to the same addition. Pick the tone that fits the publication, then use its spacing rules for dashes.
Punctuation choices shape emphasis. A colon signals that the next words answer a question raised by the first clause; a semicolon connects two complete thoughts more evenly. A colon cannot repair an incomplete sentence before it.
Practice and Check Your Answers
Choose a correction for each sentence before reading the explanations. You may find more than one sound revision.
- The team brought: pencils, paper, and a camera.
- The interview revealed one obstacle the meeting room was locked.
- The designer adjusted the headline the editor checked the caption.
- We prepared for: rain, wind, and a late bus.
1. “The team brought pencils, paper, and a camera.” Remove the mark because “brought” needs its objects. Another option is “The team brought three supplies: pencils, paper, and a camera.” The added words make the opening complete.
2. “The interview revealed one obstacle: the meeting room was locked.” Both sides can stand alone, and the second identifies the obstacle. A sentence with a colon works here because the first clause prepares the reader for an explanation.
3. “The designer adjusted the headline; the editor checked the caption.” The clauses are related but neither explains the other, so a semicolon is a clear choice. A period would work as well.
4. “We prepared for rain, wind, and a late bus.” Remove the mark between the preposition and its objects. You could instead write “We prepared for three possibilities: rain, wind, and a late bus.”
The most common snag is a colon placed immediately after a verb or preposition. Cover the words that follow it and read the opening aloud. If the opening leaves you waiting for an object, remove the mark or rewrite the opening as a complete clause.
