Servers and hosting
Snapshots and backups
A snapshot freezes a server's disk at a point in time for a quick rollback. A backup is a copy somewhere else. You want both, for different reasons.
A snapshot records the state of a virtual machine's disk at one moment. Taking one is nearly instant, and rolling back restores the server to exactly that state. That makes snapshots the right tool before an upgrade, a configuration change or anything you may want to undo in the next hour.
A snapshot is not a backup. It lives on the same storage as the server, so it does not survive a failure of that storage, and a long-lived snapshot slows the disk and grows with every change. Take one before risky work, and delete it once the work is confirmed.
A backup is a copy of the data on different hardware, ideally in a different place, kept on a schedule with several generations. For a VPS that means your own job that copies the data off the server, or the provider's backup product if it offers one, and a test restore now and then. A server you cannot rebuild from a backup is a server you do not control.