How to sign a PDF on laptop—do I need an electronic or digital signature?

If your laptop is a Mac, the built-in Preview app lets you add a handwritten signature to a PDF for free, without uploading the document.

1. Open the PDF in Preview.
2. Click Show Markup Toolbar, then Sign > Create Signature.
3. Use the trackpad to write your signature, or the camera to capture your signature from white paper.
4. Click the saved signature to insert it, then drag it into position and resize it.
5. Save the PDF. Use File > Duplicate first if you want to keep an unsigned original.

A handwritten signature added this way is an electronic signature when used to sign the document. A certificate-based digital signature also provides a way to verify the signer’s certificate and detect changes made after signing. Preview’s signature tool doesn’t provide that.