How to Use Preview to Edit PDFs on Mac

Preview is a free app that comes with every Mac, and it is surprisingly powerful for working with PDF documents. You can use it to fill out PDF forms, add your signature, highlight text, add notes and comments, merge PDFs, and more — all without paying for Adobe Acrobat or other expensive PDF software.

To open a PDF in Preview, double-click the PDF file in Finder. If it does not open in Preview by default, right-click the file, select "Open With," and choose "Preview." Once the PDF is open, you can read through it by scrolling or using the arrow keys.

To fill out a form, click on any form field (text box, checkbox, or dropdown) and type your information. Preview recognizes most PDF form fields automatically. If a form field does not respond to clicking, you may need to use the Text tool instead — click the "Markup" toolbar button (it looks like a pen tip in a circle) and then click the "T" (Text) button to add a text box where you need to type.

To add your signature, click the Markup toolbar button, then click the "Sign" button (it looks like a signature). If this is your first time, you will be asked to create your signature. You can do this by signing on your trackpad with your finger, holding a signed piece of paper up to your Mac's camera, or signing on your iPhone. Once created, your signature is saved and you can reuse it on future documents. Click your saved signature and it will appear on the PDF — drag it to the correct location and resize it by dragging the corners.

To highlight text, click the Markup button and select the Highlight tool (the marker icon). Then click and drag over the text you want to highlight. You can change the highlight color by clicking the dropdown arrow next to the highlight tool.

To add notes and comments, use the "Note" tool in the Markup toolbar. Click anywhere on the page to place a note. You can type your comments inside the note, and it will appear as a small colored square on the page. This is useful for reviewing documents and leaving feedback.

To merge two PDFs, open the first PDF in Preview, then go to View and make sure "Thumbnails" is checked (so you see page thumbnails in the sidebar). Open a Finder window with the second PDF and drag it from Finder into the thumbnail sidebar of Preview. Drop it where you want the pages to be inserted. Then save the file by pressing Command + S.

Remember to save your changes by pressing Command + S or going to File then Save. If you want to keep the original unchanged and save a modified copy, go to File then "Export as PDF" and give it a new name.