You can use iCloud or iTunes to automatically back up iPhone.
Important: Backups for music, movies, or TV show purchases are not available in all countries. Previous purchases may not be restored from iCloud Backup if they are no longer in the iTunes Store, App Store, or iBooks Store.
Use iCloud Backup. When you first sign in with your Apple ID, iCloud Backup turns on automatically. iCloud backs up iPhone daily over Wi-Fi, when it’s connected to a power source and is locked. iCloud backups are encrypted automatically so that your data is protected from unauthorized access both while it’s transmitted to your devices and when it’s stored in iCloud. Purchased content, iCloud Photo Sharing, and My Photo Stream content don’t count against your 5 GB of free iCloud storage.
Music not purchased in iTunes isn’t backed up in iCloud, but can be restored by syncing with iTunes on your computer.
When you back up using iCloud, you can’t simultaneously use iTunes to automatically back up to your computer, but you can use iTunes to manually back up to your computer.
Stop or resume iCloud backups. Go to Settings > iCloud > Backup, then turn iCloud Backup off or on.
Back up immediately on iCloud. Go to Settings > iCloud > Backup, then tap Back Up Now.
Back up with iTunes. Open iTunes on your computer, then connect iPhone. Click the iPhone button in the upper-left corner of iTunes, then click Summary in the sidebar. To make a manual backup, click Back Up Now (below Backups). To turn on automatic iTunes backups, click “This computer” (below Backups). Automatic backups are made whenever you connect iPhone to your computer.
To encrypt your backups, select “Encrypt local backup” (below Backups). You need to select this to back up Activity, Health, and Keychain data.
Some media files (such as songs, videos, and some photos) aren’t backed up, but can be restored by syncing with iTunes.
View or remove iCloud backups. Go to Settings > iCloud > Storage > Manage Storage.
View or remove iTunes backups. Open iTunes on your computer, choose iTunes > Preferences, then click Devices. Encrypted backups have a lock icon in the list of backups.
If you replace your iPhone, you can use its backup to transfer your information to a new device.