About ePub 3
When you unzip an ePub 3, you see one file and two folders:
- File: Mimetype
- Folders: META-INF and OEBPS
The META-INF folder, which contains the book's metadata information, can contain one or multiple files, but it must contain a container.xml file. This file tells iBooks how to process the rest of the ePub package.
The OEBPS folder* contains the book's content, metadata, style, and table of contents.
In the OEBPS folder, you must include these files:
- XHTML files for your content, which can include include text, images, and media. The table of contents, a navigation file, is often named toc.xhtml.
- A file named content.opf, which describes the metadata, the manifest (what files are in the OEBPS folder), and the display order of those files.
You can also include a cascading style sheet (CSS) in the OEBPS folder to describe the styling and layout of the book.
*The name of this folder might vary.
About ePub 2
Like ePub 3, ePub 2 also has the mimetype file and the META-INF and OEBPS folders. Structurally, the two formats are very similar, but ePub 2 contains a .ncx file instead of the navigation file.