e-book formats made simple

It starts off simply so I’ll try to keep it like that.

Various manufacturers of e-book reader devices have developed their own software and, in conjunction with that, have also devised their own proprietary file formats, although not normally from scratch.

Some of these file formats have become popular, so other software has been developed by various people and organisations so that the files can be read on other devices – especially smartphones, tablets, laptops and PCs.

One big influence on all of this has been a body that has attempted to establish a standard – with some degree of success. That body is the International Digital Publishing Forum (IDPF) – the originator of a widely adopted format called “EPUB” (you may also see it referred to as ePUB, ePub, EPub or epub). If you have an e-book reader there is a high chance it can read EPUB files. The most marked exception is the Amazon Kindle. Amazon promotes and sticks to its own proprietary format.

Most e-book reader devices, and e-book software running on devices like phones and tablets, use what are called “device independent variable formats”. All that means is that the files will display on a variety of different devices and the layout of the document isn’t fixed. In fact, the layout varies not only from one device to another but also with the settings selected by the user. One consequence of this is that there are no fixed page sizes or page numbers, so navigation works in much the same way as it does for web pages – by means of hyperlinks that can be clicked on by the user.

All of that is okay for fiction or simple non-fiction, but, if having a fixed layout is important, as it often is for non-fiction, this approach has severe limitations.

It’s not surprising, then, that a portable document format developed by Adobe some years ago continues to be popular, since it maintains fixed layout very well. I refer to Adobe Portable Document Format. Files produced to this standard are often referred to as “pdf files” – after the initial letters, which are also the letters used for the file name extension (.pdf).

Manufacturers of some reader devices have made a point of ensuring their devices can display Adobe pdf files as well as a selection of the more popular variable formats.

Here is a short list of the more popular file formats. They are often referred to and identified by the letters used for their file extensions, so that’s the way I’ve set out this list.

  • epub – IDPF’s EPUB standard for e-books (widely adopted)
  • fb2 – FictionBook
  • lit – Microsoft Reader
  • lrf – Sony Reader
  • mobi – Mobipocket (compatible with Amazon Kindle)
  • opf – Open Electronic Package (Open eBook)
  • pdb – eReader (formerly Palm Digital Media)
  • pdf – Adobe Portable Document Format
  • azw – Amazon Kindle

Of these formats, I would say that the two key ones for free documents are epub and pdf, but these formats are extensively used commercially, too.

Armed with that information you should be able to read descriptions of reader devices and identify what files they can be used with.

If I go any further it will start to get more complicated so I’ll stop there.

Well, nearly! If you want to find out more try these two links:


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