A mark of punctuation ( : ) used after a statement (usually an independent clause) that introduces a quotation, an explanation, an example, or a series. In addition, the colon usually appears after the salutation of a business letter (Dear Professor Legree:); between the chapter and verse numbers in a biblical citation (Genesis 1:1); between the title and subtitle of a book or article (Comma Sense: A fundamental Guide to Punctuation); and between numbers or groups of numbers in expressions of time (3:00 a.m.) and ratios (1:5)