How to use a PDF outline on Mac
Scrolling through a three-hundred-page report is hopeless. Its own table of contents is not.
Most long documents are published with a structure: parts, chapters, sections. When that structure is stored in the file, a reader can show it as a list you can click. It is the single most useful thing in a long report and the one people most often do not know is there.
The outline pane is free and always will be. There is nothing to sign up for and nothing is watermarked.
Finding it
Open the sidebar (⌘+1) and choose the outline pane — the second of the five. If the document carries an outline, you get a nested, clickable list of its sections. Click any entry to go straight there.
What it is good for
- Getting the shape of a document before reading it. Two minutes with the outline tells you more about a report than ten minutes of scrolling.
- Jumping between distant sections. Checking the definitions in an appendix against a clause in the body is one click each way.
- Knowing where you are. The entry for the section you are in is marked as you scroll.
- Splitting the document later. A document with an outline can be split at its own section boundaries, which turns a bound report back into chapters in one step.
When a document has no outline
Plenty do not — anything scanned, anything exported carelessly, anything short enough that nobody bothered. The pane will simply be empty, and that is a fact about the file rather than a problem with the reader.
Two things help. Bookmarks let you mark the places you keep returning to and build your own list as you read. Thumbnails let you navigate by what pages look like, which is often just as fast.
The outline is the structure the document was published with: it came with the file and is the same for everyone. Bookmarks are yours — the places you marked because you wanted to come back to them. Both are in the sidebar, in panes of their own.
Publishing documents that have one
If you produce documents other people have to read, an outline is the cheapest kindness you can offer them. It is also one of the things the accessibility check looks for, because a screen reader uses the same structure to let someone move through a document by section rather than by page.
Frequently asked questions
What is a PDF outline?
The table of contents stored inside the document — the parts, chapters and sections it was published with. A reader shows it as a nested list you can click to jump around.
Why does my PDF have no outline?
Because whoever produced it did not include one. Scans almost never have one, and plenty of exported documents do not either. It is a property of the file, not of the app reading it.
What is the difference between the outline and bookmarks?
The outline came with the document and is the same for everyone. Bookmarks are places you marked yourself. Each has its own pane in the sidebar.
Can I split a document at its outline?
Yes. Splitting at the document's own section boundaries is one of the four ways to split, and it turns a bound report back into chapters in a single step.
Does an outline matter for accessibility?
It does. A screen reader uses the same structure to move through a document by section, which is why the accessibility check looks for one.