What happens when a reader finishes your e-books? What's the first thing they see? What's the first thing they do? Back-matter is extremely important.
Presuming you have done your job as a writer well, it's a golden opportunity to draw readers into your world.
The basic components of effective back-matter are fairly straightforward: blurbs for and/or links to your other books, links to whatever social media presence you have, a short note requesting reviews, and, most important of all, a link to your New Release Mailing List.
If you don't have a mailing list already, you need to set one up immediately.
It's one of the most powerful tools at your disposal.
Without an effective method for collecting readers' emails (which I'll get to), every time you have a sales spike, every time you go on a free run, you are missing out on a huge opportunity to build a sustainable future for yourself as a writer.
Authors and publishers regularly gripe about Amazon.
They fear depending on a third party.
They worry about diversification and independence.
But many of them don't do the single most important thing to build that independence and ensure that their future financial health is not at the mercy of someone else.
Without a mailing list, most of your readers will still find your other books.
Amazon's system does a pretty good job of recommending books by the same author, and they aren't too hard to find if a reader noses around a little anyway.
Outside of Amazon, it's a little more challenging - given the deficiencies of its competitors - but not impossible.
But even if the various retailers' systems for recommending other titles by the same author were perfect, having a mailing list would still be crucial.
You don't want to wait until Amazon's system eventually gets around to recommending the next book in the series to your readers; you want them to buy that new release during launch week to win your book crucial visibility right from the start.
In the traditional publishing world, when a big author like Dan Brown or Stephen King has a new release, it's accompanied by a big marketing budget, and you will see ads all over the place: newspapers, billboards, and public transport.
The main aim of this advertising is not to bring new readers to these authors, but to announce to existing readers that the book is out.
The hope is that enough fans will hear about the new release and buy it during launch week - thus pushing it high in the print bestseller lists, giving the book lucrative visibility from which it will likely kick on and sell a ton more.
The strategy for self-publishers and e-books is somewhat similar, but doesn't require the same kind of marketing spend - or indeed any.
If you have been diligently collecting readers' email addresses from the beginning, you will already know the power of your mailing list.
Hitting that list when you release a new book can really launch it up the charts, first gaining you traction on the various Hot New Releases lists for your chosen categories, and then hopefully pushing you onto the respective Best Seller lists.
Without such a mailing list, you are merely hoping that your existing readers hear about your new book, and that they buy it relatively quickly.