A colon can be used in several ways. It is important to make sure that a colon is preceded by an independent clause (a sentence that is grammatically correct on its own) when used in the context of a sentence.


Examples

Using a colon to present a list

I have four favorite colors: green, blue, red, and purple.

Using a colon to provide more information

I'll tell you what she's doing: she's stealing our muffins!

Using a colon to lead into a quotation

Liz Newman stated her thoughts clearly:

"I have never been so distraught in my life.  The actions of that man are far beyond my comprehension.  I hope they put him away for a long time."

Colons are typically used before quotations that are more than seven words long.  Otherwise, a comma is appropriate.

Using a colon to show a subtitle

Deep Sea Diving: The Mystery Below

Using a colon in a professional introduction

Dear Dr. Pecard: