Online backup, also known as remote backup, is a method of offsite data storage in which files, folders, or the entire contents of a hard drive are regularly backed up on a remote server or computer with a network connection. 

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.