The Document Navigation pane is a new feature of Word 2010. It allows you to quickly and easily navigate through your document, which is especially useful when you are working with lengthy documents.
To display the Navigation pane:
The Navigation Pane will now be displayed on the left.
To search within your document, type in the Search Document text box.
The main view in the Navigation pane lets you browse the headings in your document. You can drag and drop the headings to different positions instead of copying and pasting sections.
By clicking the middle tab in the Navigation pane, you can browse the pages in your document by viewing thumbnails of the pages.
The third tab allows you to view results of your current search.