A separate copy of data, used to restore when original data is lost or corrupted.
Backup is a copy of data kept separate from the source system so it can be Restore when needed.
The commonly mentioned principle is 3-2-1: keep three copies of data, across two different types of media, with one copy stored at a different location. With data encryption malware, one more condition is needed: at least one copy cannot be overwritten from the running system.
A critical distinction in the contract: replication is not the same as backup. Replication copies every change to another location, including accidental deletions and encrypted data.
