How can I add password to PDF for protection from Windows 11?

There are two different types of PDF password protection, so the first step is to decide what you want to protect:

• Document open password, sometimes called a user password: The recipient must enter the password before the PDF can be opened.
• Permissions password, sometimes called an owner password: The PDF can be opened normally, but actions such as editing, copying, printing, commenting, or extracting pages can be restricted. 

For files containing sensitive information, the document open password is the more important option. A permissions password alone does not prevent someone from viewing the content.

Windows 11 does not include a built-in feature for adding PDF passwords. Microsoft Edge can open and annotate PDFs, but it cannot encrypt them with an open or permissions password.

Adobe Acrobat supports both types of protection, but its full PDF protection and editing workflow may be more than you need for a simple task. For basic password protection, a free desktop editor such as PDFgear is usually sufficient and easier to use.