It's always been a bit of a conundrum with document content, the balance between what you want your readers to see and what they should be able to take and edit.
You want it to be easy to open and read, but not have everyone take your content for themselves.
The Internet's famous for being a playground for plagiarists, but you don't want your intended reader to necessarily feel like you don't trust them.
If however, your documents contain sensitive or commercial content, you could be losing money by handing that information to sets of readers you never intended.
On the other hand, if you may content strictly password protected, you may alienate your intended viewers.
Take into account who your targeted reader(s) are.
Is it going to go to a company's email that has a receptionist and intranet as a filter? How sensitive is the material? You'll need to decide which level of encryption should apply to your set of circumstances.
There are several layers of protection available from most PDF creators.
You can control which images or videos may be copied and printed, or which text can be highlighted, dragged and dropped into someone else's word processor.
You can make a document password-only, and then limit the ability of the reader to copy the information contained, or make it password-protected with only the reader being able to edit the content.
There are features that allow digital signature of documents only by an approved signer, and which prohibit further editing of text and images.
You can later access a feature that allows you to see who viewed the documents, what was edited or copied and when.
Keep in mind that most security measures must be taken when your initial document is saved.
For instance in Adobe Acrobat, when you're saving the document, it will give you a whole host of security and encryption options, but if you don't save it with them then, none of them will apply when your reader receives the document.
A document can contain several layers of password.
For instance, a PDF file can require an open document password (user) and then a password to change the security settings (master).
If you want both levels of security, each password should be different.
The levels vary.
You can go with No Changing the Document, to No Content Copying or Extraction, or Disable Accessibility altogether to prevent anyone from copying content or pictures.
You might want readers to be able to edit documents and images for review by you.
You can save a PDF free of security measures, allowing anyone to edit, copy, share and print.
You could make the document available for General Editing, Comment and Form Field only, where users can make any changes except extracting comments or printing.
You can make forms that only allow the user to fill in form fields, with or without electronic signature.
You can make the form so that the user may only print it, for filling out manually and return to you via regular mail.