Cybersecurity glossary
What is backup?
Also known as: 3-2-1 backup, immutable backup, offline backup
Definition
A backup is a separate copy of data that can be restored after deletion, failure or attack. The 3-2-1 rule means three copies, on two types of storage, with one off-site.
Why it matters
Against ransomware, at least one copy should be offline or immutable so an attacker cannot encrypt or delete it. Backups protect availability, not confidentiality: they do not stop stolen data from being leaked.
A backup is only proven when you have restored from it. Test restores on a schedule and time how long a full recovery takes.
Common questions about backup
- What is the 3-2-1 backup rule?
- What security policies does a small business need?
- What are the differences between using an authenticator app and a security key for two‑factor authentication?
- Can ransomware affect OneDrive?
- Does an authenticator app transfer to a new phone?
- Can two-factor authentication be turned off?
Sources
Related Guides
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