Colons

Colons

A colon (:) is a punctuation mark used as a separator. It is also called a full colon.

Colons are seen:
  • At the end of an introduction (e.g., I saw the following: ants, a mouse and a rat.)
  • Before an end-of-sentence appositive (e.g., He needs just one trait: discipline.)
  • Before quotations (e.g., Here's my advice: "Don't jump.")
  • In references, ratios, times and titles (e.g., Read Matthew 2:1 before 11:00.)

Examples of Colons in Introductions

A colon can be used after an introduction.
  • Lee likes the following pies: cheese, chicken and mushroom, and beef and ale.
  • The Victorian printing set is missing the following characters: Q, R, K and the question mark.

Examples of Colons with Appositives at the End of a Sentence

A colon can be used to introduce an appositive. (An appositive is an "equal term" that renames something previously mentioned.)
  • He blamed his divorce on one thing: beer.
  • (Here, the appositive is beer. It renames one thing.)
  • There are two reasons why I don't believe the alibi: there's no visa and he's scared of flying.
  • (Here, the appositive is there's no visa and he's scared of flying. It renames two reasons.)
It might be useful to think of a colon as an equals sign (=). The noun on the left equals the noun on the right. (Appositives are nouns or noun phrases.)
  • I would like to change just one aspect of your draft: the words.
  • (one aspect = the words)
  • I have one piece of advice for those of you who want to receive the Lifetime Achievement Award: Start early! (Actress Shirley Temple)
  • (one piece of advice = Start early)
    (When the appositive is a sentence, it can be written with a capital letter.)
Sometimes, the ideas either side of the "equals sign" are a little harder to marry up.
  • I have made an important discovery: alcohol, taken in sufficient quantities, produces all the effects of intoxication. (Playwright Oscar Wilde)

Examples of Colons in References, Ratios, Times and Titles

A colon can be used as a separator in references, ratios, times and titles.
  • Genesis 1:1 starts "In the beginning God created the heavens and the earth."
  • (Here, a colon has been used as a separator in a Bible reference.)
  • It's myth that the ratio of women to men in Nottingham is 6:1.
  • According to a study by the University of California, the happiest hour of the day is between 19:00 and 20:00.
  • (Times of the day are more commonly written without colons, e.g., 1900 and 2000.)
  • The marathon world record is 2:02:57 (set by Kenya's Dennis Kimetto in Berlin in 2014). The 100m world record is 9.58 (set by Jamaica's Usain Bolt in Berlin in 2009). The 800m world record is 1:40.91 (set by Kenya's David Rudisha in London in 2012).
  • (Colons are used in timings greater than a minute.)
  • Many scenes for "Pirates of the Caribbean: Dead Man's Chest" were actually filmed at sea because it is so difficult to replicate water digitally.
  • (A colon is often used to separate a title from a subtitle. A semicolon (;), a comma and the word or are also commonly used for this purpose.)

Examples of Colons with Quotations

A colon can be used to introduce a quotation:
  • The guides on Gibraltar Rock always give the same advice: "Leave the apes alone, and they will leave you alone."
Be aware that a quotation can be preceded by a colon, a comma or nothing. You should opt for a colon when the introduction is an independent clause (i.e., could stand alone as a sentence).

You could also opt for a colon if the quotation itself is an independent clause, especially if you intend to start it with a capital letter.
  • The prisoner uttered: "Leave me alone."
  • (You could use a comma here.)
This is covered in more detail in the entry on quotation marks.

Why Should I Care about Colons?

There are three good reasons to know about colons.

(Reason 1) Use an end-of-sentence appositive to mix up your writing style, for emphasis and to show off a little.

Using a colon to introduce an appositive at the end of a sentence is not common in everyday writing, but it is a good tool to keep in your back pocket for mixing up your sentence structures to keep your writing interesting. Also, an appositive at the end of a sentence has the feel of a punchline and is an effective way to create emphasis. And, yeah, an end-of-sentence appositive will do one other great thing for you too: showcase your writing skills.
  • His success is attributed to one thing: determination.
  • (Using this sentence structure emphasises determination.)

(Reason 2) Don't use a colon like a semicolon.

A semicolon (;) can be used to merge two closely related sentences into one when the writer feels that a full stop is too much of a speed bump between his sentences. You can't use a colon for this. (Remember, a colon is like an equals sign when it extends a sentence. In other words, the text on the right must be an appositive (i.e., a renaming) of something on the left.)
  • Many receive advice: only the wise profit from it. [wrong]
  • (The text on the right is not an appositive of anything on the left. This is two closely related sentences. A semicolon would have worked here, but a colon doesn't. This is a badly transcribed quotation by Author Harper Lee.)
  • If stock market experts were so expert, they would be buying stock: they would not be selling advice. [wrong]
  • (The text on the right is not an appositive of anything on the left. A colon doesn't work here.)
Similarly, don't use a semicolon like a colon. Don't use a semicolon to introduce lists (a very common mistake), and don't use a semicolon to introduce an appositive.

(Reason 3) Avoid a colon to introduce a list if your introduction is not an independent clause.

If you're using a colon before a normal list (i.e., not a vertical list like bullet points), to keep things grammatically pure, try to write an independent clause for your introduction (shown in bold).
  • The team will be the following: Fred Bloggs, Joe Bloggs and John Doe.
  • (The introduction for this list is an independent clause so the colon is justified.)
  • The team will be: Fred Bloggs, Joe Bloggs and John Doe. [wrong]
  • (This is a little untidy because the introduction is not an independent clause. The use of the colon would likely raise a tut from strict grammarians.)
When introducing a vertical list (e.g., bullet points), there is far more leniency.
  • The team will be:
  • (1) Fred Bloggs.
    (2) Joe Bloggs.
    (3) John Doe.

    (Be aware that some of your readers might view even this as sloppy.)
The example below is tidier because the introduction is an independent clause.
  • The following points were noted during fire-safety survey:
  • (1) Fire exits blocked by empty PC boxes.
    (2) Batteries dead in smoke detectors.
    (3) Waste-paper bins used as ashtrays.

    (The introduction is an independent clause. Well done. Tuts avoided.)
Many writers craft their introductions to include the word following, which helps to create an independent clause that justifies the colon.
  • The winners are: John, Sarah and Simon. [wrong]
  • (This is untidy. "The winners are John, Sarah and Simon" would be safe.)
  • The winners are the following: John, Sarah, and Simon.
  • (An introduction with the following might feel incomplete because it's obvious there is still more to come, but, from a grammatical perspective, it's good enough to create an independent clause.)
Let's not pretend this isn't pedantry, particularly with regard to needing an independent clause to introduce bullet points. The example below (which features a colon on each line) is fine, and it has no independent clauses.
  • Contact us by:
  • (1) Phone: 01908 311267
    (2) Email: colin@lion-tamers.co.uk
    (3) Twitter: @liontamers

Key Points

  • There are three good reason to use a colon with an appositive at the end of sentence: to spice up your writing, to emphasise a point and to show off.
  • You can't use a colon to merge two closely related sentences into one. That's what a semicolon is for.
  • When introducing a list with colon, consider using the words the following to create an independent clause to justify your colon.
  • When introducing a list that isn't a vertical list (e.g., bullet points), avoid a colon if your introduction is not an independent clause.
  • When introducing a quotation, consider a colon if your introduction or the quotation itself is an independent clause.
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