I was reading This answer and came across this section in it (emphasis mine):

In addition to selling via the big eBook outlets, offer sale of DRM-free (but watermarked, if you like) ebooks in multiple formats on your web site and/or through outlets specializing in DRM-free ebooks. There are a growing number of ebook consumers who are tired of DRM, and their desired rate of consumption, at least in the fiction market, is far higher than the supply serving them.

Now, I get DRM-free, I'm a gamer and DRM is a huge pain in the ass, but I don't understand what formats of DRM-free eBooks there are? Are these just different file types (e.g .pdf, .docx, .txt), or is it something else?

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    How does Google not help you? E.g. en.wikipedia.org/wiki/Comparison_of_e-book_formats And then look at en.wikipedia.org/wiki/Comparison_of_e-book_readers to understand why you need different formats.
    – user5645
    Commented May 19, 2015 at 8:31
  • Hmm, that web page is debatable. What is the definition of "e-book format"? I don't think most people would call an MS Word doc file or a plain text file an "e-book format". The author of that page seems to consider any format that can be used to store text on a computer an "e-book format".
    – Jay
    Commented May 19, 2015 at 13:44
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    I'm voting to close this question as off-topic because it is not about writing.
    – hildred
    Commented May 19, 2015 at 13:58
  • I consider word processing documents and text files to be e-book formats in the same way I think pdf's are. Commented May 19, 2015 at 16:08
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    I'm voting to close because not only is it broad, but it's unclear. If you want to know what formats of e-books exist, that's a very broad question. If you want to know what DRM-Free e-books are available, that's not... clearly stated. Or are you wondering what the difference between DRM-Free e-books are with "regular" e-books? It's all just very confusing. @Memor-X, if you could reword your question, I think we can keep it open. It might not be about writing... but I would say it's about publishing.
    – Ice-9
    Commented May 21, 2015 at 14:55

2 Answers 2


They are different file types, but they are file types understood by ebook readers. Specifically the three most popular are epub, mobi, and pdf; although there are others. By the way Calibre is capable of converting between them.


There exist multiple file formats. More or less usual for e-Books are epub, mobi/azw (Kindle), pdf, txt, html and djvu. You can add DRM to pdf, epub and azw, but you can also create files of these formats without DRM.

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