A PDF owner password is a password used to set certain document restrictions (more on these below) on PDF files.

In Adobe Acrobat, this is called the Modify Permissions Password. Depending on the PDF reader or writer you are using, you may also see the PDF Owner Password referred to as the PDF Permissions Password, Restrictions Password, or Master Password.

As of the latest PDF version, the following document restrictions can be set with an owner password:

Depending on the PDF writer you use, a few of which are mentioned in the next section below, you should be able to allow some restrictions while blocking others. For example, you might be able to disable copying of text and images but enable printing, which is useful if you want to distribute a PDF but discourage duplicating portions of your own work.