iTunes creates a backup of photos in your Camera Roll or Saved Photos album, and backups of text messages, notes, call history, your Favorites list, sound settings, and more. Media files, such as songs, and some photos, aren’t backed up, but can be restored by syncing with iTunes.
When you connect iPhone to the computer you normally sync with, iTunes creates a backup each time you:
Sync with iTunes: iTunes syncs iPhone each time you connect iPhone to your computer. iTunes won’t automatically back up an iPhone that isn’t configured to sync with that computer. See Syncing with iTunes.
Update or restore iPhone: iTunes always backs up iPhone before updating and restoring.
iTunes can also encrypt iPhone backups to secure your data.
Encrypt iPhone backups: Select “Encrypt iPhone backup” in the iTunes Summary pane.
Restore iPhone files and settings: Connect iPhone to the computer you normally sync with, select iPhone in the iTunes window, and click Restore in the Summary pane.
For more information about backups, go to support.apple.com/kb/HT1766.