I made an app using PhoneGap, and in the beginning I could fill in an ID, this was optional however so I just left it to the standard one, not knowing what is was.
When I tried to upload the app to the play-store I had to change the ID to some not existing ID. I went ahead and changed the ID in the config.xml file to a reverse domain name, as they advised.
But still my question remains:
I of course did some research before asking, but I could find very little on this subject.
From the documentation:
id: the unique identifier for your application. To support all supported platforms, this must be reverse-domain name style (e.g. com.yourcompany.yourapp)
This is to make your app unique in the playstore. To avoid naming collisions between app in the play store.
Read more about Reverse domain name notation .