A colon (:) works like an arrow. The part before it is a complete sentence that promises something; the part after it delivers: a list, an explanation or a quotation. Like the semicolon, it needs a complete sentence in front of it.
Key idea
Use a colon after a complete sentence to introduce a list, an explanation or a quotation. Don’t put a colon right after a verb (are, is, include) or a preposition (of, such as).
Why it works
The colon tells the reader, “Here it comes.” That only makes sense after words that are already complete: “I have two favorite fruits” sets up the list; “My favorite fruits are” is still waiting for its own words.
Worked example: Fix a colon after a verb
“My favorite fruits are: apples and pears.”
- Cover everything after the colon: “My favorite fruits are.” That is not a complete sentence.
- Either drop the colon or rewrite the first part as a complete sentence.
Answer: “My favorite fruits are apples and pears.” or “I have two favorite fruits: apples and pears.”
Worked example: An explanation and a quotation
Where do the colons go?
- “The answer was clear: we needed a bigger tent.” The second part explains the first.
- “Strunk’s second rule is short: ‘In a series of three or more terms with a single conjunction, use a comma after each term except the last.’” A complete sentence introduces the quotation.
Answer: After “clear” and after “short.”
Common mistake
Putting a colon after a verb or a preposition (“The kit includes: …”, “made of: …”, “such as: …”). Test: cover everything after the colon. If what is left isn’t a complete sentence, take the colon out. Colons also have a few set jobs: times (10:30), and the greeting of a formal letter (“Dear Ms. Park:”), where the colon is traditional.