Portable Document Format files, PDF files can be locked and password protected by several ways. And they carries several meanings as well. Some password protected PDF file can be viewed and read easily but we’ll need to input password to copy the text and images from it. Besides copy paste, the PDF file can be password protected to publish it in print media by disabling or password protecting the Printing ability of the document. Unless you read eBooks in printed form, it’s not necessary to unlock these PDF as most of the time you read it in your favorite eBook reader.