Your iPhone gets backed up to one of two places: iTunes on your computer or iCloud. Before installing iOS 7 learn how to back-up your data and restore the content on your iPhone, iPad, or iPod touch using iTunes or iCloud. So here three useful sites on how to back-up before you upgrade to iOS 7.
- How to back-up and restore your content(Apple.com)
* Backup of purchased music is not available in all countries. Backup of purchased TV shows occurs only in the United States. Previous purchases may not be restored if they are no longer in the iTunes Store, App Store, or iBooks Store.
- CNET provides how to do a manual back up(CNET.com)
- What to do before downloading iOS 7(Mashable.com)