When you read articles about how to write novels, you’ll often encounter the advice that you shouldn’t use prologues, or perhaps even epilogues. As with many pieces of well-meant advice in life, it’s an over-generalisation which errs on the side of caution. The real advice should be to avoid using prologues and epilogues poorly.
First, a quick definition of those terms as they pertain to novels. A prologue is an introductory section, usually a short one, and almost always set apart from the main story in terms of time — but all of those qualities can be varied if the author wishes. An epilogue is a section at the end of a book, again usually brief, and often serving as a conclusion which occurs after the primary arc of the story.
Now, a quick aside to list some things you should definitely try to do when you write a novel: hook the reader as quickly as you can, avoid boring them, and focus on what’s happening rather than on background details. Hopefully those are all obvious. You can now probably deduce why prologues in particular have been given an unfairly bad reputation: they’re regularly misused.
The most common misuse of prologues is for world-building or scene-setting. Fantasy and sci-fi novels can be particularly susceptible to this, because they have to introduce the reader to worlds substantially different from our own, and novelists love to share all the little details they’ve dreamed up. The problem is that, as a reader, the last thing you want is to pick up a new novel and immediately have to push through something like an encyclopaedia article or a history book before you get to the actual story. Writers who use prologues as scene-setting not only misunderstand what prologues are for — which is almost always to tease and entice the reader by giving a slice of story whose relevance will shown later — but they also misunderstand what readers want. It’s too easy for writers to forget that they themselves are also readers, and that they’ve been bored by slow-starting tales too.
Epilogues are less contentious, particularly in our age of mid-credits and post-credits scenes in visual entertainment media. An epilogue can bring closure, and give the reader a little bit more time with characters they’ve come to care about. Epilogues are a resolution and a treat, and are inherently harder to misuse, for the simple reason that if your reader reaches the epilogue then they probably want as much more of your story as you’re willing to give them.
Prologues, done right, are a huge asset to a story, and they also readily allow setting up an initial few of your tale’s core questions. They’re economic and liberating, and their detached nature allows for immediate impact; the cold open of written narrative. They should not generally be world-building, exposition, history, and so on, because those things most often defer reader interest, and thus can kill the book.
They should be the start of the exciting and intriguing bit of the novel — which is the whole thing — even if the protagonist isn’t there yet. Learn the difference, and prologues will be a valid and valuable tool for telling your stories.