Use of colon ...

Today I'm going to talk about the colon. Even though rules are rather easy some people have difficulty using a colon. Once we understand these simple rules it will become very easy for us to use the colon and never make the same mistakes again.

I used Larry Trask's University of Sussex website as a reference for this study.

• Colon
  
  Basically we use a colon to explain or elaborate the idea that preceeds that colon. In other words, you introduce a general topic and then you can use a colon followed by an explanation of that same topic.
  
  
  1. For almost every case a colon is preceeded by a complete sentence and it can be followed by an incomplete sentence. That incomplete sentence might be a list or a simple word.
     Example: Over 30 years, there were several factors that led to the current situation: bad management, corruption and excess spending.
     
     
  2. Very ocassionaly, we can invert that order and place the explanation before the general topic. This is not very common and should be used very sparingly.
     Example: Bad management, corruption and excess spending: these were the main factors that led to the current situation.
     
     
  3. The colon can also have a few minor uses.
     
     1. When you cite the name of a book that has a title and subtitle you use a colon to separate them.
        Example: I've been trying to buy John Howard's book Lazarus Rising: a Personal and Political Autobiography.
        
        
     2. When you cite pasages from the Bible.
        Example: The story of Menahem is found in II Kings 15:14–22.
        NOTE: For this particular case you DON'T use a blank space after the colon.
        
        
     3. When you write ratios
        Example: Men outnumber women in the Executive Committee by 7:2.
        NOTE: in formal writing, it is preferable to write ratios in words. Example: Men outnumber women in the Executive Committee by seven to two.
        
        
     4. In American English the colon is used to separate hours and minutes giving a time of the day.
        Example: 10:30
        NOTE: In British English a full stop is used for this purpose. Example: 1.30
        
        
     5. In formal letters and when citing references to published work.
  
  
  NOTE: A colon is NEVER preceeded by a space and ALWAYS followed by a space in normal use.
  The colon is NEVER followed by a dash or hyphen.
  Usually, the colon is NOT followed by capital letters, however, in American English this happens often.
  The colon or any other mark SHOULD NOT be used at the end of a title that introduces a new section of a document.
  

Kangas

Source: University of Sussex