A restricted Acrobat document, or PDF, is password protected. PDFs support two security levels---one to open and view the document, and another to allow various levels of editing and printing. You'll need Acrobat Pro to change security restrictions and make changes to the document itself. Within the editing and printing security settings, you can set various restriction levels, such as the ability to fill out a form or change the PDF layout. Depending on how the creator of the PDF applied security settings, to change the document's restrictions, you'll need one or two passwords---one to open and view the document and one to change editing and security settings. Acrobat requires that these two passwords be different.