Did you know that Mac OS X 10.7+ comes with full disk encryption for Mac built into the operating system? Though Mac Mountain Lion includes FileVault 2 hard drive encryption software, it’s not turned on by default.
In order to take advantage of Mountain Lion’s hard drive encryption software, you will need to turn FileVault 2 on. You’ll do this by navigating to the System Preferences app on your Mac. Once launched, click on Security & Privacy followed by FileVault. You will need to click the padlock to unlock this section before being allowed to turn on FileVault. Before you enable full disk encryption for Mac with FileVault, be aware that all users of your Mac will need an account to your computer along with a password to unlock the encrypted hard disk.