Username or EmailPassword
No, they aren't "bubbles", nor are they called "bubbles" by Apple in English. They are called "badges" by Apple and any Apple developer worth half their salt.
The concept isn't even hard to understand - "you have X amount of items that you have yet to look at". So for Mail, that is emails. For Calendar that is new appointments. For Messages that is sms/imessage. For other apps, it depends on what the developer is trying to convey - but generally it's going to be "items I have synced for you in some way shape or form." Edited 2013-02-20 13:21 UTC