With iCloud, Apple has made it easier than every to backup your iPhone or iPad. iCloud backups are stored on Apple's servers, so if your iPhone or iPad ever gets broken, lost, or stolen, you can rest assured that all your photos, accounts, documents, Health data, HomeKit configurations, and other settings aren't lost along with it. If you didn't enable iCloud backup when you first setup your device, you should definitely enable it now!
How to enable iCloud backups on your iPhone or iPad
Launch the Settings app on your iPhone or iPad.
Tap on iCloud.
Tap on Backup.
Turn On the option for iCloud Backup.
iCloud will attempt to back up your data every 24 hours or so, as long as your iPhone or iPad is connected to Wi-Fi and plugged in to charge. Most of the time this will happen while you sleep.
If you've never backed up to iCloud before, the first backup can take a while. After that, iCloud will only upload the changes you've made since the last backup, which is much faster.