In a blog first published on August 11, 2007, I helped you understand how to use colons with lists. In this blog, I’d like to help you with other uses of the colon.
Rule 4: Use a colon instead of a semicolon between two sentences when the second sentence explains or illustrates the first sentence and [...]

Before computers, we used our typewriters to underline book titles and we placed quotation marks around article titles. Some organizations still prefer this method. However, current style manuals recommend
italicizing book titles and magazine names (impossible to do on a typewriter) and using quotation marks around articles.
Example: I read Lord of the Flies in high school.
Example: [...]