The fastest way to highlight a PDF depends on what program you're using

Most PDF readers have a built-in highlight tool that works the same way: select the text, click the highlight button, and choose a color. Adobe Acrobat Reader, Preview (on Mac), and most free readers like Foxit or Sumatra PDF all include this feature. On Windows, Preview is not available, so you'll use either Adobe Reader or a free alternative. On Mac, Preview comes with your computer and handles highlighting without installing anything else.

The steps differ slightly between programs, but the principle is identical. You're marking text with a colored overlay that stays in the document when you save it. Some programs let you highlight shapes and images too, not just text.

Key Takeaways

  • Adobe Acrobat Reader, Preview (Mac only), Foxit, and Sumatra PDF all have highlight tools built in and require no extra software.
  • To highlight text, select it with your mouse or trackpad, then click the highlight button and pick a color.
  • Highlights save into the PDF file itself when you save the document, so they stay there when you open it again.
  • If your PDF reader doesn't show a highlight button, look in the Tools menu or the annotation toolbar, which may be hidden by default.

Highlighting in Adobe Acrobat Reader

Open your PDF in Adobe Acrobat Reader. Look for the toolbar at the top of the window. Click the highlight tool — it looks like a marker pen and is usually in the annotation section. If you don't see it, click the Tools menu and select Annotate, then look for the highlight icon.

Once the highlight tool is active, click and drag across the text you want to highlight. A color palette will appear. Choose your color — yellow is the default, but red, green, and blue are usually available. The text will be highlighted immediately. If you want to change the color of a highlight you just made, right-click it and select Properties to adjust the color.

When you're done highlighting, save the document by pressing Ctrl+S (Windows) or Command+S (Mac). The highlights will stay in the file.

Highlighting in Preview on Mac

Open your PDF in Preview, which is the default PDF viewer on Mac. Click the Markup Toolbar button in the top right — it looks like a pen in a circle. If you don't see it, go to Tools and select Annotate.

In the toolbar that appears, click the highlight tool (it looks like a marker). A color picker will show up. Select your color, then click and drag across the text you want to highlight. You can highlight multiple sections without clicking the tool again — just keep dragging across different text.

Save the document by pressing Command+S. Preview will save the highlights into the PDF automatically.

Highlighting in free PDF readers

Foxit Reader and Sumatra PDF both have highlight tools, though they're accessed differently. In Foxit, click Comment in the menu bar, then select Highlight. In Sumatra, go to Edit and look for Annotate or Highlight depending on your version.

Once the tool is active, select text by clicking and dragging, then choose your highlight color. Both programs save highlights into the PDF when you save the file. If you're using an older version of either program, the menu locations may differ slightly — check the Help menu or the program's documentation for your specific version.

What to do if your PDF reader doesn't show a highlight tool

Some lightweight PDF readers don't include annotation tools. If your reader doesn't have a highlight feature, you have two options: switch to a reader that does, or use a different approach like adding text notes or bookmarks instead.

If you want to keep using your current reader, download Adobe Acrobat Reader or Foxit Reader — both are free and work on Windows, Mac, and Linux. They're larger programs than minimal readers, but they include full annotation support. Alternatively, if you only need to highlight occasionally, you can open the PDF in a web browser (Chrome, Firefox, Safari, or Edge all have built-in PDF viewers) and use the browser's highlight feature, though browser highlights don't always save permanently.

Highlighting shapes and images in PDFs

Most PDF readers can only highlight text, not images or shapes. If you need to mark up an image or draw attention to a specific area, use the drawing tool or rectangle tool instead. In Adobe Reader, click Tools > Annotate and select Draw or Rectangle. Draw a box around the area you want to mark, and choose a color that stands out.

In Preview on Mac, use the Sketch tool or Rectangle tool from the Markup Toolbar. Both let you draw shapes over images or non-text content. These shapes save into the PDF the same way text highlights do.

Saving and sharing highlighted PDFs

When you highlight text in a PDF and save the file, the highlights become part of the document. Anyone who opens that file will see your highlights. If you want to share a PDF with highlights but keep the original unmarked, save a copy first, then highlight the copy.

Some programs let you export a summary of your highlights. In Adobe Reader, go to File > Export and look for an option to export comments or annotations. This creates a separate document listing all your highlights and notes, which is useful if you're studying or researching and want to review just the marked sections.

Frequently Asked Questions

Can I highlight a PDF on my phone or tablet?

Yes. Adobe Reader, Foxit, and most PDF apps for iOS and Android include highlight tools. Open the PDF, tap the annotation or markup button (usually a pen or marker icon), select highlight, choose a color, and tap the text you want to mark. Highlights save into the file the same way they do on a computer.

Why can't I highlight text in my PDF?

The PDF may be locked or protected. Some PDFs are set to prevent editing or annotation. Try opening the file in a different PDF reader — sometimes a file that's locked in one program can be annotated in another. If it's locked in all programs, you may need the password to unlock it, or the document owner may need to change the permissions.

Do highlights stay in the PDF if I email it to someone?

Yes, as long as you save the file after highlighting. When you send the PDF, the highlights go with it. The person who receives it will see all your marks. If you don't want them to see your highlights, remove them before sending or send the original unmarked version instead.

Can I change the color of a highlight after I've made it?

Yes. In Adobe Reader, right-click the highlight and select Properties, then choose a new color. In Preview, click the highlight and use the color picker in the Markup Toolbar. In other readers, the method varies — check the program's menu or right-click the highlight to see what options appear.

What's the difference between highlighting and underlining in a PDF?

Highlighting places a colored overlay behind text, while underlining draws a line beneath it. Both are annotation tools. Highlighting is better for drawing attention to whole phrases or sentences. Underlining is better for marking specific words or when you want a less obtrusive mark. Most PDF readers include both tools in their annotation menu.