A document section is a portion of a word-processing document, such as a chapter, to which you can apply formatting different from the rest of the document. For example, a section can have different page numbering, background images, headers and footers, and table of contents.

A word-processing document is all one section unless you specifically add more sections to it.

In Page Thumbnails view, when you tap a page thumbnail and then tap it again, a yellow highlight appears behind all the pages in the same section.