Colons bring attention to whatever follows them. The main
grammatical uses for colons are as follows:
1.
To introduce a lengthy quote, phrase, or clause that continues, defines,
or intensifies the idea of whatever comes before the colon.
For example, consider the following:
There is one thing I admire about
Denise: her patience.
My favorite quote from Plato is:
“Wise men speak because they have something to say; fools because they have to
say something.
In the first example, the colon is
calling attention to a phrase that defines the main idea in the sentence.
In the second example, the colon is
introducing a quote.
2.
In formal and business letters at the end of the greeting.
Consider the following:
To whom it may concern:
Dear Mr. Royce:
In these cases, the colon is used
at the end of the greeting of a formal business letter.
3.
After the words “the following” or “as follows”, usually to introduce a
list.
For example:
In his suitcase, the police found
the following: two footballs, one basketball, and an eyedropper.
Here, a colon is used to introduce
a list after the words “the following”.
4.
To mark that someone is speaking (this is commonly seen in play scripts).
Consider the following example:
Jason: Would you like to go
fishing with me, son?
Jared: Sure, that would be great!
In this example, the colon is used
to mark speech.