iCloud backup
When a device is signed into iCloud using your Apple ID, certain data, such as calendars and contacts, is kept in sync between the device and Apple’s servers. This data is then synced to all your other devices signed in with the same Apple ID, but it also means there is an up-to-the-minute, device-independent archive of your data in the cloud, which you can restore to a replacement device if you lose your old one or upgrade to a new one.
That’s the theory, anyway. In real life, backups can be a minefield. For backups to be made, your device must be powered, able to access the internet, locked, and
