A colon can refer to two different things: a punctuation mark and a part of the digestive system. Here, we will focus on the punctuation mark. A colon is a punctuation mark consisting of two equally sized dots aligned vertically). It is used to introduce an element or series of elements that illustrates or amplifies the information that precedes the colon. Some common uses of a colon include:

• Introducing a list: A colon can be used to introduce a list of items. For example, "The grocery list includes: milk, bread, eggs, and cheese."

• Introducing an explanation or elaboration: A colon can be used to introduce an explanation or elaboration of what precedes it. For example, "She had one love: Western Michigan University".

• Introducing dialogue: A colon can be used to introduce dialogue. For example, "Reporter: What is the Western Edge? Dunn: It is a strategic plan for promoting student success".

• Clarifying composition titles: A colon can be used in titles that express two parallel ideas. The words on either side of the colon should be able to stand on their own. For example, "He wrote Crisis Management by Apology: Corporate Response to Allegations of Wrongdoing".

It is important to note that a colon is nearly always preceded by a complete sentence, and what follows the colon may or may not be a complete sentence.