People store a lot of very important information in their phones. It is difficult to be sure that you have protected this information well enough, in case something happens to your phone.
There are two iCloud backup facilities built into iOS. First, is iCloud backup for your content. In this system, you identify which types of information you want to be backed up in iCloud. The information you save this way is available for synching across all of your devices. Many people back up their contacts, calendars, and photos this way.
The other way is to use iCloud Backup to back up the whole phone. This method includes the apps and set up of your iPhone so that you could completely recreate it if it is lost.
To set up iCloud backup:
Go to the Settings App
Tap on your name at the top of the screen
Tap on iCloud
Then scroll down until you see iCloud Backup and tap on it
If it is not already green as shown here, tap on the slider to turn it on.
Tap on Back Up Now if you haven’t backed up before, or if you are going to do a major update or need to reset your phone. Otherwise, the back ups will happen automatically.
If you’re using iOS 10.2 or earlier, go to Settings > iCloud > Backup.
The backup will happen automatically when the following conditions are all met:
- Device is plugged into power
- Device is connected to Wi-Fi
- Device’s screen is locked (it is asleep not turned off)
- There is enough available storage in iCloud for the backup size.
The iCloud Backup will contain:
- Data from the apps you have
- Apple Watch backups
- Phone settings
- Organization of your Apps and Dock
- Photos and videos
- Purchased items if purchased from Apple, like music, movies, TV shows, apps, and books
- Voicemail password
Note that the backup is of items that are stored on your phone, not items that are already stored in iCloud.
Here is Apple’s description of the iCloud backup of an iPhone. https://support.apple.com/en-us/HT207428