Imagine this: You own a laptop, and on that laptop ore your bank records, email, taxes, papers, pictures, contact list--practically your whole life. Then one day, someone steals your laptop, and with it all your information. Sure, maybe your have a backup and you can get it back, but now all your data is in the hands of a thief. If the thief stole your laptop, there is certainly no logical reason to think they will keep your data safe. At best, they would wipe your hard drive, destroying it. But now, you don't have to worry about such scenarios.

Encryption programs offer real-time data encryption program, meaning that all your data is encrypted while it is being written to the hard drive. Typically, whenever you store a file on your computer, the operating system writes the file as it would appear in the document.

This is a sentence↔ OS ↔ Hard Drive: This is a Sentence

However, encryption programs reside between the operating system and the hardware so that everything that is written to the hard drive is encrypted and decrypted on the fly. Without the encryption key, the data is unreadable. It would be a feat for someone to decrypt a hard drive if it is encrypted with encryption software.

This is a sentence↔ OS ↔ Drive Encryption ↔ Hard Drive: fdggsddhs4jkmaQ43TDK

After installing data encryption, every time you boot your computer you will see a screen that asks you to enter the password you supplied. Without that password, the data on the drive is unreadable--even by another computer with drive encryption installed.

Many operating systems come with data encryption already installed. Mac OSX has FileVault. Certain versions of Windows Vista have BitLocker. Windows XP users and versions of Vista without BitLocker can download and install TrueCrypt, a free drive encryption program.