Backup describes the process of copying stored data onto another medium to avoid data loss. To avoid simultaneous loss of the original data as well as the safety copy through external influences (e.g. fire damage), the stored data is usually also kept spatially separated.
Making regular backups is an absolute requirement for audit-proof archiving. A structured backup – at least including daily, weekly and monthly media – is recommended, which – in the case of data loss that was discovered at a later point – allows a system reset without incurring data loss.