When your laptop is lost or stolen, you aren’t just out $800 (or more). Your personal information is also accessible to whoever takes it, even if you have a password.

“Unfortunately, a typical password-protected user account does nothing to protect your data,” says Dennis Stewart, a security engineer at CipherTechs. “While the password will prevent someone else from logging into your computer, an attacker can still use other methods to copy files off.” If thieves remove the hard drive and put it into another computer, they have access to any files you have stored on it. In some cases, they can even reset the password on your PC and gain access to your email, passwords and other personal information.

Thankfully, you can protect your data against both of these types of attacks with encryption. “Encryption is a mathematical process used to jumble up data. If important files or whole devices are encrypted, there is no way to make sense of them without the key,” Mr. Stewart said. That means if thieves try to access your information, they’ll find only a jumbled mess unless they have your password, and they won’t be able to simply reset that password if the device is encrypted.

Encrypting your hard drive isn’t some super-technical process that only security experts can perform, either — anyone can do it on his or her computer at home, and it should take only a few minutes to get up and running.