A colon can be used in several ways. Examples of this are shown below. 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—
Using a colon to provide more information—
Using a colon to lead into a quotation—
Using a colon to show a subtitle—
Using a colon in a professional introduction—
Dear Dr. Pecard:Sources: http://www.grammarmonster.com/lessons/quotation_marks_lessons.htm
http://grammar.ccc.commnet.edu/grammar/marks/colon.htm