There seems to be quite a buzz lately about prologues. Many agents and editors have apparently developed an aversion to them. Some agents have said on their blogs that if they get a submission that contains a prologue they will automatically reject it because they see it as laziness on the author's part, the "easy" way out to present backstory. Others have said they will not read the prologue but go straight to chapter one and see if it makes sense without the prologue. (And, no, it probably won't make sense because the author wrote chapter one knowing that certain things were explained in the prologue. Why explain them again in chapter one?) One agent says that to have a prologue means the reader has to start the book twice because there are two beginnings.
As a writer, I disagree with all of the above. I'll explain in more detail. But first, out of curiosity, I decided to see how many authors took the easy way out by using a prologue. I looked through thirty-six books I have laying around my office. They were in a variety of genres. I found it was divided right down the middle: half had prologues, half did not. Some of the authors who used prologues and made their readers start the book twice were Mary Higgins Clark, Karen Marie Moning, Tami Hoag, Barbara Delinsky, Carla Neggers, Wendi Corsi Staub, Dorothy Garlock, and P. J. Parrish. I felt much better about my own prologues after seeing that I was in good company with these bestselling authors!
Now, let me explain from a writer's perspective why we use and like prologues. (By the way, I got feedback from other writers as well to ensure that I wasn't completely wrong in this belief.) I can sum it up in three reasons: prologues are effective, easy, and they show (don't tell). How many times have we had the latter pounded into our thick skulls?
Okay, so why are prologues effective? A prologue is indeed backstory, but it portrays an event from the past that will directly affect your character's life in the present. It can be hundreds of years ago, or minutes ago, but it should lead to a turning point in a character's life, something that will change your character's life forever. The turning point is the reason the rest of the book exists.
From a writer's perspective, it is much more effective (and easy) to put this event into an action scene, often in a prologue, that immediately engages the reader and allows him to "see" the backstory and be thrust right into the crux of things rather than to be "told" about it in the first two or three chapters through boring introspection, narrative, and contrived dialogue. By showing this all-important event with action, the reader is immediately engaged and inherently understands the emotions, the motivation, the conflict, the stakes–everything–without being told. Even movies use the efficiency of prologues.
As for starting a book twice, I've never heard a reader complain that they had to start a story twice because of a pesky, gosh-dern prologue. If anything, it whets their appetite and they burrow down deeper into their chair and dive right into chapter one because they are now invested in the protagonist on every level. They understand inherently what is driving the story and the characters.
Sometimes prologues are not necessary because they are nothing more than a character's history. And sometimes they really are too long. I won't argue either of those points. But, as a writer, I believe prologues can be a good and simple tool with which to hit the ground running. Call it lazy if you will, but if prologues didn't work so well, writers wouldn't use them. Many times they just make good sense for choosing the best, the easiest, and the most effective way to engage your reader and "show" your story.