The principal problem encountered with colons is that writers tend to view them as synonymous with the semicolon. The colon should be used only in a few very specific circumstances:
- Use a colon in headings (Writing With Style: Conversations on the Art of Writing)
- Use a colon before listing a series of things (My mother asked me to buy several items from the store: milk, toast, eggs, juice, and butter.)
- Use a colon before a quotation (As Jeffrey Lyons put it: "There is no truth to equal one grounded in aesthetics.")
- Use a colon between two clauses when the second one provides an explanation of the first. (Her look could only mean one thing: utter disappointment.) Whereas the semicolon divides clauses that are of equal significance, the colon divides clauses that are related but differ in degree of clarity.
Decide where and how a colon should replace the underlined punctuation (NOTE: no underlined punctuation below). In some cases, you may have to choose between two grammatically acceptable versions of a sentence in favor of one that simply clarifies the sentence's meaning.
1. I have several errands to run today. I have to go to the store, meet my friend for coffee, work for six hours, and finish a psychology paper.
2. America was a nation of innovation and new beginnings; it was also a nation that espoused the conventions and prejudices of the Old World.
3. I couldn't decide whether to entitle the paper "Story, History, Methodology, Herodotus and the Ideologies of Ancient Greece" or "Rhetorical Sideshows-- Variety and Ideology in Ancient Greece."
4. You shouldn't let these things get you down. Remember the old adage, "Whatever doesn't kill you can only make you stronger."
5."I didn't say I was angry about it," she replied. "I only wish you had told me that you were going to be late."
6. It is difficult to accomplish so many things at once. It is difficult to budget one's time effectively.