How to Highlight a PDF: Step‑by‑Step Methods for Every Platform

Why Highlighting PDFs Matters

Highlighting lets you mark important passages, prepare study notes, or share key points with colleagues without altering the original content. Unlike printing or annotating on paper, digital highlights stay searchable, editable, and portable, making them essential for students, researchers, and professionals.

Built‑in Highlight Tools by Operating System

Windows 10/11 – Microsoft Edge

Edge includes a native PDF viewer with highlighting:

• Open the PDF in Edge.
• Click the Highlight icon (a pen tip) in the toolbar.
• Select text, choose a color, and click Apply.
• Save with Ctrl + S to embed highlights.

macOS – Preview

Preview is macOS's default PDF reader and supports highlighting out of the box:

• Open the PDF in Preview.
• Choose Tools → Annotate → Highlight Text or press Shift + Command + H.
• Drag over the desired text; the default yellow can be changed via the markup toolbar.
• Export the file to keep the highlights permanent.

Linux – Okular

Okular, common on KDE desktops, provides robust annotation:

• Open the PDF in Okular.
• Click the Review button, then select the Highlight tool.
• Highlight text and optionally add a comment.
• Save the document (File → Save) to embed annotations.

Free Third‑Party Desktop Applications

Adobe Acrobat Reader DC (Windows/macOS/Linux)

Adobe's free reader offers reliable highlighting:

• Download from adobe.com and install.
• Open the PDF, select the Comment pane, then click the Highlight Text tool.
• Choose a color, highlight, and click File → Save.

Foxit Reader (Windows/macOS)

Foxit is lightweight and supports multiple highlight colors:

• Install Foxit Reader.
• Use the Comment toolbar → Highlight.
• After marking, go to File → Save As to keep changes.

Highlighting PDFs on Mobile Devices

iOS – Files or Books App

Both native apps let you annotate PDFs without extra software:

• Open the PDF in Files or Books.
• Tap the Markup (pen) icon.
• Select the Highlight tool, choose a color, and swipe over text.
• Tap Done to save.

Android – Google PDF Viewer / Drive

Google Drive's built‑in viewer includes highlighting:

• Upload the PDF to Drive and open it.
• Tap the Comment icon, then the Highlight tool.
• Drag over the text, then tap Done to save.

Online Highlight Tools (No Installation Required)

When you cannot install software, web‑based editors work in any browser.

PDFescape

Free for files up to 10 MB:

• Go to pdfescape.com and choose "Free Online".
• Upload your PDF, select the Highlight icon, apply colors, then click Save & Download.

Smallpdf

Simple drag‑and‑drop interface:

• Visit smallpdf.com/highlight-pdf.
• Drop the file, use the toolbar to highlight, then download the annotated PDF.

Best Practices for Persistent Highlights

To ensure highlights remain visible to all viewers:

• Save the file after annotating. Some viewers only store highlights in a temporary session.
• Embed highlights. Use "Save As" or "Export" options that embed annotations rather than creating a side‑car file.
• Choose standard colors. Yellow, green, and pink are universally supported across readers.

Comparative Table of Popular Highlighting Solutions

Common Troubleshooting Questions

Why don't my highlights appear on another device?

Some apps store annotations locally (e.g., in a .xfdf side‑car file). Always use the "Save" or "Export with annotations" feature to embed them in the PDF.

Can I highlight a scanned PDF?

Scanned PDFs are images; you need OCR (optical character recognition) first. Free tools like Adobe Acrobat Reader's "Scan & OCR" or online services such as iLovePDF can convert images to selectable text, after which highlighting works.

How do I remove or edit a highlight?

Open the PDF in the same tool you used to create the highlight, select the annotation, and press Delete or choose a new color.

Conclusion

Highlighting a PDF is straightforward once you know which built‑in or third‑party tool matches your workflow. Whether you're on a desktop, mobile device, or need a quick online solution, the methods above let you add, edit, and preserve highlights efficiently—keeping your important information accessible for years to come.