Zotero offers six PDF annotation methods.

Option 1: Highlight Text

Click the icon that looks like the letter 'A' surrounded by a square, located in the toolbar just above your PDF. It will display the words 'Highlight Text' if you hover over it.

Use your cursor to select any text on the PDF.

Release the button on your mouse when you're happy with your text selection.

The Zotero program, displaying a PDF. Some text of the PDF has been highlighted in yellow.

An entry will appear on the left-hand 'Annotations' menu, which includes the page number of your highlighted text, and a preview of the text you selected. (If you don't see this left-hand menu, click on the far left icon on your PDF toolbar, which reads 'Toggle Sidebar' if you hover over it. That should make this menu appear.)

From here, you can edit this annotation. If you click on that entry in the left-hand menu, you'll see a prompt to 'Add comment.' Click those words to start typing. Your comments will be saved automatically.

The Zotero program, displaying a PDF. A comment visible on the left-hand panel annotates the highlighted text.

Option 2: Underline Text

Click the icon that looks like the letter 'A' underlined, located in the toolbar just above your PDF. It will display the words 'Underline Text' if you hover over it.

Use your cursor to select any text on the PDF.

Release the button on your mouse when you're happy with your text selection.

The Zotero program, displaying a PDF. Some text of the PDF has been underlined in pink.

From here, you can edit this annotation. If you click on that entry in the left-hand menu, you'll see a prompt to 'Add comment.' Click those words to start typing. Your comments will be saved automatically.

Option 3: Add Note

With the 'Add Note' feature, you can place a comment at a particular point on the PDF.

Click the square icon on the PDF toolbar that identifies itself as 'Add Note' when you hover over it.

Click on the place on the PDF where you'd like to put the note, then begin typing. Your comments will be saved automatically.

The Zotero program, displaying a PDF. A yellow sticky note is added to the text with an annotation.

Option 4: Add Text

With the 'Add Text' feature, you can place text directly onto the PDF.

Click the icon on the PDF toolbar that looks like the letter 'T' and displays the words 'Add Text' when you hover over it.

Click on the place on the PDF where you'd like to put the text, then begin typing. Your comments will be saved automatically.

The Zotero program, displaying a PDF. The words "My text here" appear on the PDF.

Option 5: Select Area

The 'Select Area' tool is useful if you want to highlight a photo, drawing, or other figure within the text.

Click on the square icon that reads 'Select Area' when you hover over it, then draw around the section you choose.

Release the button on your mouse when you're happy with the area.

The Zotero program, displaying a PDF. A figure has been highlighted.

To add comments to this image, click on its entry on the left-hand annotation menu. You'll see the words 'Add comment' appear; click on those words and start typing. Your text will be automatically saved.

Option 6: Draw

The 'Draw' tool is useful if you want to freehand draw anything directly on the PDF.

Click on the icon that looks like a pen with a squiggle beside it. It reads ''Draw' when you hover over it. Place your mouse in the spot you choose to draw, and click when you're ready to begin drawing. Release the button on your mouse when you're finished.

The Zotero program, displaying a PDF. Green and red check marks and x's are drawn directly on the PDF.