ePub eBooks

Key Information

ePub is simple to make it as universal as possible. Avoid complex layouts and formatting, only use simple tables and don't use invisible topics. Only a..z, A..Z, 0..9 and _ are permitted in topic IDs in ePub eBooks!

The ePub format (file extension .epub) is a standard for e-books created by the International Digital Publishing Forum. It is quickly becoming widely established, with many thousands of ePub eBooks already in circulation. It is already supported by the multi-platform Adobe Digital Editions software reader, the Sony Reader hardware eBook reader, the Apple iPhone and iPod Touch, mobile phones and many other devices and software readers.

See ePub Resources for more details, including sources for reader software and devices.

The ePub format

The eBook format is completely open and fully documented. An ePub eBook consists of basic XHTML for the book content, XML for descriptions, and a zip archive file with the extension .epub containing all the files.

Features and pros and cons of ePub eBooks:

File extension:	.epub
Format:	A single zip archive file containing the XHTML and XML files and other components.
Platforms:	Viewable on any platform or device for which an ePub reader is available. Includes Windows, Apple OS X, Linux, Unix, Sony Reader, Apple iPhone and iPod Touch, BeBook Reader, mobile phones and many more.
Typical use:	Truly portable
Table of contents:	Yes, not supported by all readers
Keyword index:	No
Full text search:	Yes, but search functionality depends on reader
Context-sensitive help:	No support for context-sensitive help, you cannot make direct calls to specific topics in the help
Popups:	No
Multimedia:	No
Printable by user:	Yes, but print functionality depends on reader
Pros:	Single-file, universal cross-platform format already supported by many software and hardware readers. Large number of ePub eBooks already published, likely to become a universal standard. Generally intuitive handling (depends on reader).
Cons:	This is really a dedicated format for books in electronic form. Not appropriate for application help because of the lack of context sensitive help support. No index, simple formatting only, no multimedia or popup support. No password protection. Many readers handle tables poorly.