Content encryption refers to the use of file encryption, described just below, which is a little different from disk encryption.  These terms were included in a previous post, but going over some details is always a good idea.

File encryption software is used to protect individual files.  Encryption itself means the use of an algorithm--in other words, a formula--to scramble data.  So, assuming you've got only two documents on your laptop, files A and B, you could opt to protect file A while not encrypting file B.  File encryption programs allow the end-users to protect their data on a granular basis.

The big advantage over this granular control is the fact that you can also allow multiple people to access different resources on the same computer.  Going to back to files A and B, you wouldn’t face any problems having multiple people access the computer that contains both files because the protected file can only be accessed by people with the correct username and password.

This is not possible with disk encryption.  Disk encryption is named that way since the entire hard disk is encrypted.  In this case, both files A and B are encrypted because they happen to be on an encrypted disk--it's not unlike printouts for both files being protected if they were placed in the same locked safe.

This means there are two "problems" with disk encryption ("problems" depending on what kind of solution you need--for me they're a great solution).  One, you lose the granular protection: as long as a person can access that computer, he or she can access all information stored on that computer.  Two, when you copy a file off the encrypted disk, that file will not be protected anymore, just like taking a document out of a locked safe.

This does not mean that disk encryption provides less security than file encryption.  The former is great for those instances when a computer is stolen by an outsider, since the thief won't be able to access the contents of the computer at all.

There's also the overlooked fact that people forget to encrypt important files.  If a computer employs only file encryption, and a laptop is stolen--well, are you absolutely certain that none of the sensitive files were left unencrypted?  With disk encryption, there's no need for doubts: it's either protected or not, period.  No gray areas.

On the other hand, if you frequently shoot off e-mails that include sensitive files as attachments, you'll need file encryption to ensure that the file is protected.  Yes, in case you send the e-mail to the wrong person--which happens all the time.  But also, because of how e-mail is delivered.  And when you consider that, file attachment encryption becomes necessary as well.