A colon indicates that closely-related information follows.
For information about using colons with run-in headings, see Description lists that use run-in headings.
Introductory phrase preceding colon
When a colon introduces a list, the text that precedes the colon must be able to stand alone as a complete sentence.
Recommended: The fields are defined as follows:
Not recommended: The fields are:
Colons within sentences
In general, the first word in the text that follows a colon should be in lowercase. For exceptions, see Capitalization and colons.
Recommended: Tone: concise, conversational, friendly, respectful
Recommended: When you add or update content to an existing project, remember to take these steps: review the style guide, use checklists, enlist a fellow writer or an editor to copyedit your work, and request a developmental edit if you feel that it's warranted.
See also
For more information about how to punctuate introductory material, see the sections on list introductions and code-sample introductions.
For information about when it's better to use colons than dashes, see Dashes.