About backups in iCloud and iTunes - https://support.apple.com/HT204136 - "You can copy and save the data on your iPhone, iPad, or iPod touch by backing up your device in iCloud or iTunes. If you replace your device, you can use its backup to transfer your information to a new device."
How to back up your devices using iCloud or iTunes - https://support.apple.com/HT203977 - If you back up your iPhone, iPad, or iPod touch, you’ll have a copy of your information to use if your device is ever replaced, lost, or damaged. Backups let you transfer data from your last device to your new one.
Restore your device from an iCloud or iTunes backup - https://support.apple.com/HT204184