The Colon is a punctuation mark consisting of two equally sized dots centered on the same vertical line.

The most common use of the colon is to inform the reader that what follows the colon proves, explains, or lists elements of what preceded it.

Rule 1.Use the colon after a complete sentence to introduce a list of items when introductory words such as namely, for example, or that is do not appear.

• You may be required to bring many items: sleeping bags, pans, and warm clothing.
• I want the following items: butter, sugar, and flour.
• I want an assistant who can do the following: (1) input data, (2) write reports, and (3) complete tax forms.

Rule 2. A colon should not precede a list unless it follows a complete sentence; however, the colon is a style choice that some publications allow.

• There are three ways a waitress can make a good impression on her boss and her customers:
  1. Dress appropriately.
  2. Calculate the bill carefully.
  3. Be courteous to customers.

Rule 3.Capitalization and punctuation are optional when using single words or phrases in bulleted form. If each bullet or numbered point is a complete sentence, capitalize the first word and end each sentence with proper ending punctuation. The rule of thumb is to be consistent.

• I want an assistant who can do the following:
  1. Input data,
  2. Write reports, and
  3. Complete tax forms.