Erasing and syncing replaces the contents of this i Phone with the contents of this i Tunes library.” The way that Apple recognizes which i Tunes library is linked to your i Phone, i Pad or i Pod touch is based on a Library Persistent ID key that is hidden on Mac and PC.
In i Tunes 8.2.1 and earlier, most content was stored in an i Tunes Music folder.
In i Tunes 9 and later, content is stored in the i Tunes Media folder.i Tunes software may be used to reproduce materials.
The downside is that I now have my i Tunes library on my internal hard-drive and my DJ'ing library on my external HD.
If you’re like me, your household has a few i Tunes accounts.
See the i Tunes Store Terms of Service for additional information.