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http://support.apple.com/kb/HT1766
+*You can use iTunes to sync content on your computer (such as music, podcasts, videos, ringtones, photos, email account settings, contacts, calendars, and bookmarks) with your iPhone or iPod touch.* Syncing makes sure this content is the same on your iPhone or iPod touch and computer. iTunes will also create a backup of settings and certain other information on your iPhone or iPod touch when you sync to use in case you want to restore the software on your iPhone or iPod touch or transfer this information to a different device. *Backup information includes information such as mail settings, text messages, notes, call history, contact favorites, sound settings, widget settings, certain network settings, and other preferences.* Applications purchased from the App Store are included in the backup, however they can only be successfully restored to the same device that they were backed up from.+