backup

A backup is a copy of data stored separately from the original to protect against data loss. Backups support recovery after events such as hardware failure, software errors, accidental deletion, malware, or disasters. A well-designed backup strategy balances protection, cost, and restore speed, and is part of broader data management and business continuity planning.

Backup types include full backups, which copy all selected data; incremental backups, which copy only data changed since the last backup; and differential backups, which copy data changed since the last full backup. Some systems use synthetic full backups or mirror backups. Each type affects storage requirements and recovery time.

Backups can be stored locally on disks or tapes, remotely to offsite locations, or in cloud storage. Many organizations implement a multi-location approach guided by the 3-2-1 rule: three copies of data, on two different media, with one copy stored offsite.

Key objectives include the recovery point objective (RPO), the maximum acceptable amount of data loss, and the recovery time objective (RTO), the time to restore operations. A backup plan should include tested restoration procedures and verification of backup integrity.

Security considerations include encryption in transit and at rest, access controls, and protection against tampering. Regular testing of restores, versioning, and secure key management improve reliability. Automation and monitoring help ensure backups run on schedule and that failures are detected promptly.