Cleansing Your Colon
Use a colon to introduce particular information. One of the most common uses of a colon is to signal to readers that a list will follow:
On the camping trip, please bring the following: a flashlight, a sleeping bag, two boxes of matches, and food for six meals.
If you have a list that is the object of a verb or of a preposition, you don't need a colon:
(The list is the object of the verb bring.)
(The list is the object of the preposition
To be on the safe side, use an expression such as
Use a colon to explain or give more information about what has come before it in a sentence:
In formal papers, a colon usually precedes a lengthy quotation:
To determine what is meant by “lengthy,” consult the style guide designated by your instructor or employer.
Here are other times to use a colon:
in the greeting of a business letter
To Whom It May Concern: between the hour and minutes in time
a meeting at 4:15.P.M .in dividing a title from its subtitle
My Favorite Punctuation Marks: Why I Love Colons in naming a chapter and verse of the Bible
Genesis 2:10
in naming the volume and number of a magazine
Time 41:14in citing the volume and page number of a magazine
U.S. News and World Report 166: 31between the city and the publisher in a bibliographical entry
London: Covent Garden Press
Try this Web site to test yourself on using colons correctly:

