AP® English Language and Composition · Big Idea 4 Style: Grammar, Mechanics, and Punctuation (Skills 7.C, 8.C)
7.C The Colon (STL-1.O)
A colon announces that something specific is coming: it sits after a complete statement and introduces the word, list, or explanation that delivers on what that statement promised.
A colon is a setup-and-payoff device. The words before it must form a complete sentence, one that makes a claim or creates an expectation. The words after it answer that expectation directly: a single word, a list, an explanation, even another full sentence. The colon tells the reader, whatever comes next is the specific thing the left side was pointing at. That's different from a comma, which just links or separates without making that promise. A comma says 'and here's more'; a colon says 'and here it is.'
The right side can scale up without breaking the rule. 'The problem was simple: money' uses one word to name the problem. 'The problem was simple: the district had 40 thousand dollars and needed twice that' uses a full sentence to explain it. Both work because the left side, 'The problem was simple,' is already a complete statement before the colon arrives. The payoff can be short or long; what matters is that it fulfills the setup.
This is why a colon can't follow such as or sit in the middle of a phrase like 'the reasons are.' Those constructions already point forward grammatically, so the words before the colon aren't a finished sentence, they're a fragment leaning on what follows. A colon on top of that lean breaks the rule: the left side has to stand on its own first. This sits next to semicolon and comma rules in the same unit, all testing whether a student can tell when a clause is genuinely complete.
Key terms
- Colon
- A punctuation mark that follows a complete statement and introduces the specific word, list, or explanation that fulfills it.
- Independent clause
- A group of words with a subject and verb that can stand alone as a complete sentence.
- Setup and payoff
- The relationship where the clause before the colon creates an expectation and the material after it satisfies that expectation.
- Fragment
- An incomplete group of words that cannot stand alone as a sentence, often lacking a finished thought.
Watch it explained
- How it worksHow does a colon set up a promise on the left and pay it off on the right?
- Worked exampleWalk me through He needed one thing: time, and what the colon claims that a comma would not.
- Going furtherWhat changes when the material after a colon is a full sentence instead of a single word?
- Common mistakeWhy isn't a colon allowed to follow such as or to sit in the middle of the reasons are?
Check yourself
End of topic.