EPUB is short for Electronic Publication an open e-book standard that was developed by the International Digital Publishing Forum. EPUBs were specifically designed to work with the many e-readers that are now available. If you are reading an EPUB on an e-reader and the text is too small for you, you can simply change the font size so it’s more legible. As the text enlarges, it will simply reflow to the next line to fit the dimensions of the e-reader you are using.
An EPUB is essentially a zip file. Simply click on an EPUB and change the extension from .epub to .zip, extract the file and you’ll see it is actually comprised of different folders. Without going into technical detail, each folder contains the information required to let the e-reader know how the text and chapters are to be formatted and arranged. If any graphic files, photos or illustrations were used, these will also be located in one of the folders. Upon further examination, you’ll see files with XHTML extensions which is Hypertext Markup Language, the same language used for creating web pages.
If there is one criticism it’s that the EPUB format is geared to handle text for use with e-readers so, by design, e-readers have only modest computing power when compared to your home computer. This greatly limits what an e-reader can interpret in an EPUB which directly affects what can be shown on screen. Where a printed book can have a variety of fonts, intricate graphics and formatting, when interpreting an EPUB file, an e-reader doesn’t have the capability of reproducing a book the same way. And that isn’t all. Since every e-reader uses its own proprietary software to interpret an EPUB, so will it also display that EPUB differently.
So what does that mean to the self publisher? Not much if your book is primarily text and your main concern is that your audience can read it properly and you’re not bothered by the changes you’ll see in your book’s formatting. But even when you use only basic text, you’ll see differences in your book when viewing it on different e-readers. Fonts will differ, as will headings and formatting such as line spacing and paragraph indentation to name a few. That fancy dingbat or webding you used to separate paragraphs may not be recognized by your e-reader and it might put in a question mark in its place.
Many of the sites that market e-books allow you to upload your files directly and the conversion to EPUB is done automatically. But again, they use their own software to make the conversion. When uploading your file, their software analyses it and outputs an EPUB according to its own criteria. The EPUB you ultimately wind up with may not exactly be what you hoped for. I’ve even had cases where a site rejected a completely valid EPUB because it did not support having pictures in the file.
Here at Self Publishing, I make an effort to look at your file and make the converted EPUB look its best. I view your book before hand and, if I notice any potential problems, I will let you know what to expect and work with you to make your e-book look the best it can be.