The Navigation Panel can display the following:
Attachments (at the bottom of the screen)
Bookmarks (on the left)
Comments (at the bottom of the screen)
Destinations (on the left)
Form Controls (on the left)
Model Tree (on the left)
Pages (on the left)
Signatures (on the left)
Tags (on the left)
When you select a panel, it gives you access to a set of tools related to the current display.
To show or hide the Navigation Panel
Choose View > Navigation Panels > [desired panel].
Click the arrow beside the Navigation Panels button in the View Toolbar and select the desired panel.
Click at the bottom of the vertical bar that separates the Document Panel from the Navigation Panel, to show/hide the Navigation Panel.