How to Highlight Text in a PDF and Save the Highlights

Highlights disappearing is the most common complaint here, and it has one cause more often than all the others combined: the highlight was made in a viewer that never wrote it back to the file. Getting this right is mostly about where you highlight and how you save.

Real highlights versus drawn ones

A proper highlight is a text markup annotation. It is anchored to the actual characters underneath, so it travels with the text, can be searched and listed, and can carry a note. Any PDF tool can read it.

A drawn rectangle is just a shape on top of the page. It looks similar and behaves nothing like it: it does not know what it covers, and if the page is ever reflowed or the text edited, it sits in the wrong place.

You want the first. In every tool it is the button labelled Highlight, not the one labelled Rectangle, Draw or Shape.

Where highlighting actually persists

Adobe Acrobat Reader (free) — select text, click Highlight, then File → Save. Reliable, cross-platform, and the safest default if the file matters.

macOS Preview — select text and use the highlighter button. Preview saves to the file automatically. Fully compatible with other readers.

Chrome and Edge — their built-in viewers can highlight, but saving is the weak point: depending on version, Ctrl/Cmd+S may save a copy without the annotation. Always reopen the saved file in a different reader to confirm before you rely on it.

iPhone and iPad — open in Files or Books, use Markup, tap Done. Markup writes real annotations, but be careful with the share sheet: "Send a Copy" and "Export PDF" do not always behave the same way.

Android — the built-in Drive viewer offers limited markup; Xodo and similar readers handle annotations properly.

The rule that covers all of them: highlight, save, close, reopen. If the highlight is still there after a genuine reopen, it is in the file.

Why highlights vanish

The file was never saved. The highlight existed only in the viewer's memory. Closing the tab discarded it.

A browser viewer saved a copy without annotations. The most common version of this problem, and the reason to verify.

You downloaded the file again instead of saving your copy. A fresh download from email or cloud storage is the original, without your markup.

The PDF is a scan. You cannot make a text highlight on an image, because there is no text to anchor to. Some tools silently give you a drawn rectangle instead — which is why your "highlight" is a slightly wrong-sized box. OCR the file first if you need real highlights.

The file has permissions restrictions. Some PDFs disallow annotation. The button will be greyed out or the save will fail.

Getting the highlights back out

This is the part people discover too late. Once highlights are real annotations, most readers can list them: Acrobat has a Comments panel that shows every highlight with its text and page number, and can export them. Preview has a Highlights & Notes sidebar.

If you are highlighting for research, that export is the entire value — and it only exists if you used real text highlights rather than drawn boxes, on a file with a real text layer.

When you want the highlight gone permanently

Two very different things get called "removing a highlight":

Deleting your own markup — click the highlight, press Delete, save. Easy.

Redacting — hiding text so nobody can recover it. A highlight, or a black rectangle drawn over text, hides nothing: the text is still there underneath and can be copied straight out. That has embarrassed a lot of organisations. Redaction needs a tool that genuinely removes the underlying content, not one that covers it.

For ordinary edits to the page itself — correcting the text rather than marking it — this site's editor handles files up to 10 MB and 100 pages and keeps the layout intact.

Frequently asked questions

Why do my highlights disappear when I reopen the file? They were not written to the file. Most often a browser viewer saved a copy without them. Reopen in a different reader to check, and prefer Acrobat Reader or Preview.

Can I highlight a scanned PDF? Not as real text highlights — there is no text to anchor to. You can draw shapes, or OCR the file first.

Can I change the highlight colour? Yes, in most desktop readers, usually by right-clicking the highlight and opening its properties. Useful for coding themes in research.

Will the recipient see my highlights? If they are saved into the file, yes, in any standard reader.

Does highlighting change the underlying text? No. It is an annotation layer over the page. The text is untouched.