A colon is used to introduce an item in a series of items that describe or amplify what has preceded the colon. Example: Sarah’s exercise program involves three objects: a stationary bicycle, an exercise ball, and 2-pound weights.
The colon may be used instead of the period to introduce a series of related sentences.
Example: Karen was faced with a difficult choice: Should she tell her husband what happened to the car? Or should she remain silent and get it fixed herself?
Colons are also used in URLs, but no space precedes or follows a colon in this case.
Example: An excellent place to find many versions of the Bible is http://www.BibleGateway.com/.
When a colon is used within a sentence, the word following the colon is lowercased unless it is a proper name. When a colon introduces two or more sentences, a speech in dialogue, or a Bible verse, the first word following the colon is capitalized. Example:
Philippians 3:14 states: “I press on toward the goal to win the prize for which God has called me heavenward in Christ Jesus” (NIV).