Come... on... Down!
(The Colon is a Curtain)
Remember when you were sick, and you didn't have cable (or anything better to do)? Did you happen to see a show called The Price is Right? Well, let the Writing Center tell you about it. The Price is Right was a lot like a sentence, the prizes hidden behind the curtains were a lot like the second part of sentences, and the curtains themselves were a lot like colons. The Writing Center hopes that makes everything very clear.
Sometimes the game show voice would say something like, "We have three fabulous prizes: a boat, a car, and an all-expenses-paid trip for two to sunny Puerto Vallarta!" The colon in that quote occurs at about the same time that the curtains open. Sort of like opening a curtain, a colon says, "Those things I was talking to you about (the prizes)? Here they are."
If you're prone to occasional hallucinations, as the Writing Center is, you might even think that the colon looks sort of like a curtain.
Sometimes that colon/curtain comes before a list (like the three fabulous prizes). Other times it comes between two different ways of saying the same thing. It's really a list of one. "You're going to need that snorkel when you go on the vacation of a lifetime: a trip to Cancun for Spring Break with the Writing Center!" Here, the colon shows that the "vacation of a lifetime" = "a trip to Cancun." In fact, maybe that's a better way to think about it.
The colon isn't a curtain at all. It's an equals sign.
Fine Print: Consult your professor before using colons. Colons may not be right for everyone. Do not use colons while drinking adult beverages or operating heavy, heavy machinary. Colons are also used in lots of random places, like between the chapter and verse of Biblical passages ("John 3:16"), at the beginnings of formal letters ("Dear Sir or Madam:"), showing ratio ("the ratio of good-looking snorkelers to Writing Centers was 8:1"), and separating titles from subtitles in fancy academic papers ("Star Trek and Star Wars: A Study in Contrasting Views of Vulcan Feminist Theory"). It also makes a nice smiling icon :) , but the Writing Center would never endorse using icons in an academic setting.