How to annotate a PDF

Annotating a PDF sounds simple until the notes need to be found again. A report gets highlighted in Preview on a laptop, a second copy gets marked up in Acrobat on a work machine, and the comments on a research paper end up in a separate notes file because the PDF reader on the phone didn’t save them. A month later the highlights exist, but in three versions of the same file.

This guide covers the usual ways people annotate PDFs, where those methods scatter the notes, and how to highlight and comment on a PDF in Fabric so the annotations stay with one copy of the file, available on every device you use.

How people usually annotate PDFs

The built-in tools are the first stop: Preview on a Mac, Microsoft Edge or Acrobat Reader on Windows, and the markup tools in the Files app on an iPhone. They’re free and quick for one document. Annotations are usually saved into that copy of the PDF, so the notes go wherever that file goes, and a second download of the same document starts clean.

Researchers often use a reference manager such as Zotero or Mendeley, which keep annotations alongside citations. That suits academic papers well. Notes on the papers then live apart from drafts and other writing in Google Docs or Word, and connecting an idea in one paper to a note elsewhere is manual work. Research workflow covers that wider setup.

Plenty of people still print the PDF and use a pen. Handwritten margins are good for thinking. They’re hard to search, and they stay on the desk when you need them on the train.

Step 1: Add the PDF to Fabric

On the web or desktop app, drag the PDF in, paste it, or click Upload a file. Several PDFs can go in at once.

If your PDFs already sit in a folder on your computer, the Fabric desktop app mounts Fabric as a virtual drive on Mac, Windows, and Linux. Move the folder onto the drive the way you’d move it anywhere else, and every PDF in it is ready to open and annotate in Fabric. Files on the drive take no space on your computer and stream when you open them, which helps with large scanned reports and textbooks.

For a PDF that arrives by email, forward the attachment to your Fabric email address. It accepts mail from your verified account address. On a phone, open the PDF in any app, tap Share, and choose Fabric; the mobile apps for iOS and Android both support the share sheet.

You can add a comment or tags to the PDF as you save it, which helps when you have a reason for keeping it that the document itself doesn’t explain, such as “for the Q3 pricing review”.

Step 2: Open it in reader mode and highlight

Open the PDF and it displays in reader mode, a distraction-free view with an estimated read time and a progress bar. Select a passage and highlight it. Fabric’s PDF annotations offer two modes: simple highlights for quick reference while you read, and highlights with comments when you want to say why a passage matters.

A light approach works well on a first read. Highlight what seems important, keep moving, and come back to comment on the passages that still look important the second time.

Step 3: Add comments to your highlights

Add a comment to a highlight to record what you think: a question, a counterpoint, a link to another source, or a note on what to do next. Comments stay attached to the highlighted text, and clicking a comment’s location tag jumps to that highlight in the document, which saves scrolling through a 60-page report to find the passage a note refers to.

For papers and long reports, writing a sentence in your own words next to each key highlight makes later writing faster. How to write a literature review shows how those notes turn into a draft.

Step 4: Find the PDF and your notes later

Click Search or press Cmd+F (Mac) / Ctrl+F (Windows). Fabric search reads the text inside PDFs and matches by meaning and by keyword, so describing the document is enough to find it. Results open at the exact page. Put words in quotes for exact matches, such as a clause number or a specific term.

To work across several annotated PDFs at once, put them in a folder, open it, and ask the AI assistant. It’s limited to that folder and answers with clickable references to the source, so a question like “what do these three reports say about churn?” comes back with citations you can check. Save a useful answer as a note and it sits next to the PDFs.

Step 5: Annotate a PDF with other people

To have colleagues or a client mark up the same PDF, click Share and give them commenter permission. Commenters can highlight and comment on the PDF, and Fabric’s collaboration tools thread replies under each comment. Any comment can be marked completed, which turns a reviewed PDF into a checklist of changes. External people can use shared links without signing up.

Frequently asked questions

How do I highlight text in a PDF online?

Upload the PDF to Fabric, open it, select the text, and highlight it. It works in the web app as well as the desktop and mobile apps.

Can I add comments to a PDF, not only highlights?

Yes. You can leave a plain highlight or add a comment to it. Clicking a comment’s location tag takes you to the highlighted passage.

Is there a free way to annotate PDFs?

Yes. File uploads and the reader are on Fabric’s free plan, which has storage and file size caps. See pricing for what each plan includes.

Will my PDF annotations be there on my phone?

Yes. Annotations stay with the file in Fabric, which runs on the web, desktop, iOS, and Android, so you see the same highlights on each device.

Can someone else comment on a PDF I’ve shared?

Yes. Share it with commenter permission and they can highlight and comment. They don’t need a Fabric account.

Can I search for text inside my PDFs?

Yes. Search reads the text inside PDFs and opens results at the exact page. Use quotes for exact matching.

Can AI answer questions about the PDFs I’ve annotated?

Yes. Open the folder with the PDFs and ask the AI assistant. It cites the documents it used, and you can save the answer as a note.

How do I annotate a PDF that someone emailed me?

Forward the email or attachment to your Fabric email address, then open the PDF in Fabric and highlight it there.