Bookmarks are used to make your PDF files easier to navigate, more interactive, and more useful (see Figure 1). Bookmarks provide interactive links that navigate to a specific destination. Although bookmarks typically link to a specific section of text, page number, or graphic on a page, they can just as easily link to an Internet web site or email address.
Figure 1: PDF bookmarks provide interactive links to content in your PDF files, other documents, or online. You can click a bookmark to follow a link.
To view existing bookmarks in a PDF file, click the Bookmarks tab on the left side of the Document window. This opens the Bookmarks palette. Click a bookmark to follow the link. If the bookmark's text is difficult to read, you can enlarge the size of it by choosing the Options menu in the Bookmarks palette; then choose the Text Size option. Use this command to increase or decrease the size of bookmarks. You can also wrap long bookmark lines by choosing the Wrap Long Bookmarks command.
Bookmarks can be nested to reflect a hierarchical structure; this is sometimes called a parent-child relationship. The topmost bookmark, which contains subsidiary topics that are indented and located under the main topic, is a primary topic. Not all bookmarks are nested, and your documents can contain a mixture of both nested and non-nested bookmarks.
You can click the plus sign (Windows) or triangle (Mac OS) adjacent to the bookmark to show its subsidiary bookmarks (see Figure 2). You can also click the minus sign (Windows) or triangle (Mac OS) that is adjacent to a bookmark to retract any subsidiary bookmarks that are visible. Finally, you can expand or collapse nested bookmarks by selecting a bookmark and choosing either Expand Current Bookmark or Expand Top-Level Bookmarks from the Options menu in the Bookmarks palette (see Figure 3). Similarly, if bookmarks are expanded, you can choose the Collapse Top-level Bookmarks command from the Options menu to collapse all but the topmost level bookmarks.
Figure 2: Nested bookmarks.
Figure 3: The Bookmarks palette for expanding the current bookmark.