Like a prologue, epilogues aren't always necessary in your book. In fact, they are becoming rarer and rarer. Just like prologues, many people don't even read them so if you are going to include one, make sure you have a good reason for doing so. I've listed a few of the main reasons below and I will be going through them separately and more into detail. Don't forget that these are only the main reasons, not all of them. If you have a separate reason, feel free to tell me in the comments.

a) To provide important information not in your climax or denouement.

b) To show what happens to your story's world/characters after the conflict is resolved.

c) To provide an introduction to a sequel.

d) To better convey a theme.

Generally speaking, you should aim to answer all the questions you want to within your story because some readers don't read the epilogue, especially when they don't realize there is one (it's happened before). However, sometimes having too much information all at once is just that: too much. Or maybe there wasn't the right time or situation to include it if your climax is very intense. In these cases, you can try and put it in your epilogue. Don't just list off a bunch of facts that your story was lacking before, though -- try and make it as fitting and as interesting as possible. How that can be done will be unique to every specific story.

A lot of the time your readers will be wondering how things turned out for the characters or a world that used to be controlled by a corrupt government. In that case, it would be all right to show them how the world became under new control. In this case, the epilogue should be in the future. A good word for this kind of epilogue is "closure". If that is what you and your readers desire, go ahead and include it! Chances are, if there is lack of closure in the actual book they will be looking for an epilogue to finish the book off with. This is especially good if the ending was sort of tragic, like if someone died. An epilogue can show how the other characters coped after their death and reassure the audience that they're doing all right. "Harry Potter" had an epilogue like this, as did "Divergent", and in a way, so did "The Hunger Games".

If you are writing a series, this is very commonly seen. Do any of you remember "The Incredibles"? Remember how the mole people came out of the ground as a "villain" and it showed the family preparing to fight? If that were your book, that would be a perfect introduction to a sequel. Of course, it doesn't need to be like that at all. If you wanted, you could just have the epilogue told from the villain's perspective and have them hatch a plan to destroy the world without the protagonist even realizing. This isn't uncommon.

The most important thing to remember that the conflict has been resolved before the epilogue. If you are introducing a sequel it should be introducing a new conflict.

There is no one way to do this. If your theme wasn't as clear as you would like or you want to elaborate on it but it just doesn't fit in your story, you can try and fit it into an epilogue. Again, like my first point, make sure that it is still interesting and engaging. You want your readers to finish the story feel satisfied with a fond opinion of you. Unless, of course, you killed their favourite character. . . .

You'll notice that epilogues follow much of the same ideas and structure as prologues do. As a result, some of my final tips will be very similar.

Just like your last chapter, the last sentence of your epilogue should create impact. It should provide closure and clearly say "the story is over". Don't make it something like: "Susie walked down the street." An alternative could be: "Susie walked into the sunrise and smiled; she was finally home." Not necessarily the best example, but you get the idea.

Keep it short. Epilogues don't need to drag on. The trick to holding interest is to get it over with as soon as possible. That sounds odd, but your readers didn't start the book to spend fifteen minutes reading an epilogue. They will get bored. Humans have an incredibly small attention-span if you don't keep them engaged.

If you are introducing a sequel, leave off with a cliff-hanger! Your readers will just have to read the next book if you do.

Be artistic! Like in prologues you can spice it up and make it deep with interesting analogies, other forms of figurative language and vivid scenery. The conflict should be pretty much over so you have lots of room for this now.

Back when I was talking about prologues I mentioned the kind of prologue that starts at the end. For example, an unexplained incident is in a prologue and the rest of the story leads up to that event. In your epilogue it's expected of you to come full circle. This will provide closure. Your epilogue should expand on the event in your prologue, if that makes any sense to you.

Be unique in your epilogue. It's your one opportunity to tell the story from a new perspective, even the antagonist if you want. It will be interesting to see how they act when they have been defeated. Most epilogues are told in the future -- that would be cool, too! There are lots of options for you out there.

Don't raise questions; answer them. Unless you are introducing a sequel, your epilogue is there for you to explain things, not provide opportunity for more confusion. If there's a sequel, raise as many questions as you want!

That's it! As per usual, I am always available for questions so don't hesitate. Likewise, comments are lovely. Aside from that, I'd like to thank you for reading!