An ebook is a file with a defined structure, not a document that happens to be read on a screen. EPUB is the format the trade uses, Amazon converts what you send into a format of its own, and the difference between a reflowable file and a fixed-layout one decides most of what the book can do afterwards. Checking the file before it goes anywhere is cheaper than correcting a title that is already on sale.
This guide gathers our posts on ebook files in one place: what the file is, how to check it before you upload, how to make it usable by everyone, and what each store does with what you send. Each post answers a single question and stands on its own, so start wherever your question sits rather than at the top. We add to the guide as we cover more ground, so it is worth bookmarking.
One caveat: a file that validates is not necessarily a file that reads well. Validation tells you the package is correctly assembled; only opening the book on a device tells you whether the result is any good.
What the file is
- Reflowable or fixed layout: which one your book needs, and what each one gives up.
- EPUB or PDF: what separates the two, and when a PDF is the wrong answer.
- EPUB 2 and EPUB 3: what changed between the versions, and whether it affects you.
- The NCX file: what it is, and whether a modern EPUB still needs one.
- When there is no file left: how a printed book becomes an ebook once the originals are gone.
Checking it before you upload
- Validating the file: how to run the check, and what the errors mean.
- Previewing on devices: how to see the book as a reader will, without owning every device.
- Checking someone else’s work: what to look at in a file a formatter has delivered.
Making it usable by everyone
- Accessibility in the EPUB package: what to fix, and where it lives in the file.
- The accessibility checklist: the same ground as a list you can work through, with code examples.
What the stores do with it
- Amazon’s conversion: what happens to your EPUB after you upload it.
- One file or several: whether each retailer needs its own version.
- Barnes and Noble Press: how its ebook publishing works.
- DRM: what copy protection does, what it does not, and whether to apply it.