What is an ebook?

As an author you are probably familiar with the term ebook; an e-book is a non-editable, reflowable book that has been converted to a digital format and is read on an electronic device like a computer or e-reading device, such as a tablet. There are many ebook formats that you should consider as not all formats work on all devices, and it is important that you have all the ones you need to sell your book.

What is an ebook made of?

An ebook is made up of HTML, CSS and package files. It is essentially made up of different web pages (HTML pages), styling files/code (CSS file) and is read together through a package file (.opf) and a navigation file (.ncx/toc.html).

Ebook formats


This file works like a print PDF and is best viewed on a larger screen, such as a computer screen. You navigate from page to page as you would with a print PDF, so if readers view this format on a small device, they will have to zoom in to read it. One important difference between a print PDF and ePDF is that an ePDF has internal and external linking (for example, from the table of contents to chapter headings as well as out to a website). The overall format and page layout will be maintained in the ePDF. Anyone with a PDF reader can view this document.


ePub is the most widely supported format and can be read on a variety of different devices such as tablets, smartphones, epub readers (Adobe Digital Editions/Readium) and personal computers (Wahl, 2018). The most widely used ePub format standard, at the moment, is the ePub 2 format. Older and newer e-readers will accept this standard; there is also the ePub 3 and fixed layout standard ePubs, but they are less supported. This may well change in future as more readers accept the standard. The ePub 3 standard allows for interactive elements such as sound and video and is usually used when creating textbooks and children’s books (Dube, 2019).


Mobi and .azw

Mobi files are the oldest file format for Amazon but are still very popular and widely used, especially if your book is text-only. Amazon’s latest file format is .azw and .azw3 and support reflowable and fixed layout, as well as DRM and interactivity.


Why do you need both?

Both ePub and Mobi are flowable formats, so the content will flow to the size of the screen. User-defined settings, such as font size, can affect how much of a page is displayed on screen. Thus, the overall format and page layout will not be maintained in these formats. ePubs can be read on most devices; Mobi files can be read on only a Kindle/Amazon device. ePub and Mobi are the most common types of eBook formats.


How to review your converted files

Once you have had your book converted it is essential that you review your converted files carefully to be sure the conversion is accurate. You can use an ePub reader app or you can view on your own e-reader. It is a good idea to view your ebook on multiple readers and devices as each reading/viewing experience is slightly different.

In terms of ebook reading apps, you can use Adobe Digital Editions on a PC or Mac to view ePub files and web-optimized PDF files. The Kindle Previewer (on a PC or Mac) is the tool you need to review Mobi files. If you’re reviewing on a device other than a PC or Mac, remember that some devices do not enable some features such as linking.

What do you need to check for?

To ensure your ebook is correct, take the time to review both the mechanical features and the text of the book.


Go through the book and verify that all links work properly, including navigation links, table of contents, footnotes, illustrations and index links. Make sure that links actually take readers to the right spot. For example, table of contents links should get readers directly to the correct chapter or heading, and index links should take readers to the page the entry is on.


Read or scan through the entire text to check for technical errors that were not in your source file such as added spaces or capitalisation or punctuation issues. Fonts may be approximated because ePub format supports standard fonts.

Staging Post can help you convert your book into the necessary ebook formats and advise you on how to distribute them through platforms like Amazon.


Wahl, J. 2018. ‘What is an eBook? Understanding Why They Work and How to Make Your Own.’ Learning Hub. Online: https://learn.g2.com/what-is-an-ebook. Accessed: 21 July 2020.

Dube, M. 2019. ‘What’s an ebook? Beginner’s Guide to Ebook Reading, Creation and Distribution.’ PublishDrive. Online: https://blog.publishdrive.com/whats-an-ebook/. Accessed: 21 July 2020.

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