Navigating PDFs: Bookmarks vs Table of Contents

The concept of document navigation tools such as bookmarks and tables of contents has been around for centuries. However, they're often underused or misused. I wanted to go back to the basics and discuss what these items really are today, and where they are – and are not – appropriate. What is the difference between the two, and is one better than the other?

The Table of Contents

The table of contents is usually one or more pages found towards the beginning of the document and provides a quick understanding of the document's structure: chapters, sections, subjects, etc., and the page numbers where those items can be found. Clever use of indentation can show that one topic is a part of another, larger subject or a subheading.

The advantage of having a table of contents is that it becomes a part of the content; often the table of contents references itself. This is an advantage because if you were to print a hard copy of the document, you can retain this navigation tool to quickly look up the topic of interest, determine the page number, and then use your fingers to navigate to that page.

PDF Bookmarks

Bookmark functionality is found in most PDF viewers to display the list of chapters, sections, and other headings. It works as the document structure in a special toolbar or pane, while also viewing the document content. The advantage of this navigation tool is that it goes with you, no matter where you are in the document.

It is by far the best way to navigate between sections of the document, and it also allows you to see where you are in most documents, as your current location will be highlighted. (Notice in the image how the table of contents item is highlighted with a light grey bar? This shows we're currently on that page.)

The disadvantage of PDF bookmarks is that they're only available when viewing this content in a PDF viewer that supports it. While most PDF viewers will support the display and navigation of PDF bookmarks, if you were to print the document or convert it to an alternative format, you lose this navigation tool.

Which Navigation Tool to Go With?

Ultimately, it is the delivery vehicle (electronic vs. paper) that will drive which navigation tools to use. It doesn’t make sense to navigate back to the table of contents in a document when you’re already in the middle of it, so a table of contents is not particularly useful if your documents will only be delivered electronically in PDF format. However, if you primarily, or even occasionally, generate hard copy versions of your documents, the PDF bookmarks are lost, and the table of contents becomes quite important.

Either way, PDF, which has become the standard file format for exchanging and archiving documents, provides flexible and convenient options for allowing the consumers of your documents to quickly navigate to the content they are looking for. Rendering platforms, such as Adlib, can intelligently generate these navigation tools for you by automatically analyzing the structure of your documents and incorporating that into these powerful navigation tools.