File encryption is not just the stuff of spy movies. There are plenty of practical reasons why you might decide to encrypt a single file, multiple files, or even an entire drive. If you keep sensitive digital copies of financial information such as bank statements and tax returns, you can encrypt them to make sure unauthorized users cannot get to them. You may just have documents, such as your first novel, that you do not want anyone to see. Encryption provides an extra layer of security that simple password protection cannot.