While in document view, tap the translucent tab (circled below) on the left of your screen to access or hide the Navigation Panel.
The Navigation Panel includes five options:
- Thumbnails: displays a scrollable, film-strip style list of the pages in your document.
- Outline: shows any bookmarks, outlines, or chapter entries (if applicable to your PDF).
- Annotations: lists all markups added to the file by page.
- Search: allows you to search text in the active document.
- Actions: provides a list of commonly used document-specific actions.