A Document is a piece of front or back matter. Documents are not numbered and are excluded from the EPUB Navigation Document by default.
A Chapter is a piece of body matter. Chapters are automatically numbered and are included in the EPUB Navigation Document.
Both are have different formatting options.
Yet, Documents and Chapters have many things in common:
- They encapsulate a body of text and images (which is followed by a page break in PDF and EPUB)
- They can have Tags and Keywords
- They can contain links to other Documents, Chapters and Resources
Steelkilt allows you to create create Documents and Chapters with separate commands throughout its user interface — but will assume that any imported files are Chapters (because most books contain more body matter than anything else).
Converting a Document to a Chapter (and vice versa) can be achieved with a quick change in the Chapter Settings.