How to test whether your backup actually works?

A backup you've never tested is not a real backup. Test by restoring one file from the backup to a different location and confirm it opens correctly. Do this when you first set up the backup, and again twice a year.

Setting up a backup and never testing it is like buying a fire extinguisher and never checking if it works. Many people find their backups failed silently only when they need them. Testing is simple: restore a single file, make sure it opens, and confirm the content is correct. Do this at setup time and at least twice a year.