PDF documents are probably best when you want to share the information but dont want people to edit it. Many times when information is too confidntials you need to proect the protect the pdf with a password. so the user who know the password can only view the document. There are many tools available to encrypt PDF with a password. ADOBE ACROBAT READER PRO DC have inbuilt functionality to protect the document. ADOBE READER comes with so many functionality but with a great cost too.
I have developed projects for HR departments where they need to generate protected salary slips from excel and send them automatically to the staff. I build a custom tool only to protect the PDF. it is very easy to use to protect a single PDF or multiple PDFs saved in a folder, you just need to hit a couple buttons and thats it.