A certain PDF file can be secured and its content made inaccessible by deploying encryption methods. In this process, either the entire file can be encrypted or parts of it, depending on the need.
PDF files along with Encryption options also provide password protection. The downside with this method though is the fact that one has to come up with new passwords for each file.
Yet another aspect of PDF file security is the Copy Protection. This mechanism however is redundant due to internet's expansion and must be deployed along with either of the above 2 for desired result
Digital Rights Management of a PDF file implies the permissions that individuals have for certain processes on the file such as printing, copying etc. PDF files can be made secure in this regard also.
The creator of this guide has not included tools
New York, USA