If you've read this far in this section, you should know the basics of installing an App Store app, syncing it, updating it, and deleting it. If you'd like to know more about these topics, or if you are trying to solve a problem, keep reading in this section.
For more advice on troubleshooting apps, check Apple's Support site, especially this support article: http://support.apple.com/kb/TS1702.
How are App Store apps backed up?
During a full sync of an iPhone, a backup file is either created or updated (see Understand Sync Options and Understand the iPhone Backup). At this time, data related to App Store apps installed on the iPhone are backed up. As a result, if you restore your iPhone, all the previously installed App Store apps will ...