Similar to other punctuations marks, colons provide clarity in written language by separating elements not part of the grammatical structure of main clauses. Colons perform eight basic functions in written English.
Sentences beginning with * are incorrect and are included as examples of what you should not do.
Use colons to introduce lists that are not part of the grammatical structure of the main clause. For example:
- The Preservation Department contains four units: Conservation, Processing, Binding, and Stacks Maintenance.
- I need you to pick up a few groceries from the store before you come home: milk, eggs, bread, butter, and sugar.
Do not use colons to introduce lists that are part of the grammatical structure of the clause. For example:
- *The typical class schedule includes: math, spelling, reading, social studies, science, and history.
- *The baker decorated the cake with: icing, sprinkles, jellybeans, and coconut.
Use colons to introduce quotations that are independent from the grammatical structure of the main clause. For example:
- Martin Luther King, Jr. inspired a generation with just four words of his famous speech: "I have a dream…"
Also use colons to introduce block quotations. For example:
- In November 1863, on the Gettysburg battlefield, Abraham Lincoln spoke the now most well-known words of his life:
Four score and seven years ago our fathers
brought forth on this continent a new nation,
conceived in Liberty, and dedicated to the
proposition that all men are created equal.
Do not use colons to introduce quotations integral to the grammatical structure of the clause. For example:
- *Martin Luther King, Jr. proclaimed: "I have a dream…"
- *Abraham Lincoln said: "Four score and seven years ago…"
Introduce Elaborations and Emphasizations
Use colons to introduce elaborations that provide additional details about the initial clause. For example:
- The gruesome movie is actually a love story: The lead male and lead female characters strive to find each other throughout the entire story.
- The cat has bandages on her front paws: She was recently declawed.
Also use colons to join two independent clauses in which the second clause emphasizes the first clause. For example:
- All of the roads are impossible to drive on: The roads are completely covered in ice.
- The library is completely packed with students: The undergraduates are crowded into the building studying for their midterms.
Introduce Rules and Principles
Use colons to introduce rules and principles. The first letter of the rule or principle should be capitalized. For example:
- The first rule at the pool is for the safety of all pool-goers: Do not run in the pool area or locker rooms.
- We must base our observations on Newton's third law of motion: To every action there is an equal and opposite reaction.
Use colons to introduce appositives that are not part of the grammatical structure of the clause. Appositives are nouns, pronouns, or noun phrases that modify or explain another noun, pronoun, or noun phrase. For example:
- I know who committed the murder: the butler.
- The boss appointed the perfect person to the job: you.
Use colons to separate hours and minutes in time notations. For example:
- The class is at 4:30 in the afternoon every Tuesday.
- Employees must arrive at work between 7:00 and 9:00 A.M.
Use colons to separate chapters and verses in Bible references. For example:
- God created Eve in Genesis 2:22.
- The Bible warns against rejecting wisdom in Proverbs 1:20-33.
Business Letter Salutations
Use colons at the end of business letter salutations. For example:
- To Whom It May Concern:
- Dear Sir or Madam:
The accompanying printable reference sheet of the rules for using colons in English is available for download at The Use of Colons in Written English Reference Sheet.
Capitalizing After Colons
Usually this is a style choice, so if you're writing a paper for your professor, find out what his preferred stylebook says. In APA style, the first word after a colon is capitalized if it begins a phrase that can stand alone as a complete thought.
- Rules of Punctuation: Commas, Colons, and Semicolons
- The Three Functions of Semicolons in Written English