After becoming a member of the iPhone Developer Program you must set your application ID in the Program Portal. iPhone OS uses application IDs to identify the applications you create. An iPhone application ID is made up of a ten-character bundle seed identifier and a bundle identifier. The bundle identifier can identify one application or a group of applications.
This is an example of an iPhone application ID that identifies a single application, named
MyApp: GFWOTNXFIY.com.mycompany.MyApp
Using an asterisk instead of an application name in the bundle identifier lets you share a
single application ID between a set of related applications.