To protect their work, the creators of some PDF documents will often put security settings on their PDF files. While they are allowed to be circulated, viewed, and often printed, these documents may not be edited or altered.
These creators, often professional or corporate, will choose which changes they will allow. These options or restrictions include printing, commenting, extraction, content copying, signing, filling in fields, and document assembly.
You may for example, be allowed to print or sign the document, but not allowed to extract any of its pages. Adobe Acrobat offers tools to view security properties selected by the original creators or publishers.
To change the settings and unlock protected PDF files, you must have the file’s password. This may often be provided by the creator, or perhaps a colleague, a client or a supervisor.