Portable Document Format (PDF) files are commonly used to store and share information such as contracts, reports, and other sensitive documents. Common PDF files are easily accessible and anyone can view them with the help of a PDF reader. The problem with these files, however, is that they can easily be changed or manipulated without the owner's consent. To prevent this from happening, you can protect your PDF files using password protection. There are many reasons why it is important to password protect your PDF files, let's look at four of them.