CrashPlan is an online remote back up. The rationale behind online backup is simple. By frequently (or continuously) backing up data on a remote hard drive, the risk of catastrophic data loss as a result of fire, theft, file corruption, or other disaster is practically eliminated.
With a high-speed Internet connection and a Web browser interface, the remote files and folders appear as if they are stored on an external local hard drive. Encryption and password protection help to ensure privacy and security.