3.4.1 Backups
A backup is a point-in-time copy: snapshots, logical dumps, or WAL archiving. It is useless until you have restored it once.
Why it matters
Disks fail. Migrations go wrong. Ransomware happens. Uptime is not the same as durable data.
How it is used
Automate daily (or continuous) backups. Store them in another account or region. Test restore on a schedule. Define RPO (how much data you can lose) and RTO (how fast you must be back).