What’s an Application ID? How is it different from the application package name?

Q: When setting up push notifications in the Developer Console under Application Identifier, I need to fill in the Application ID. What is it?

A: The Application ID is your app’s unique identifier, usually set in your app’s build.gradle file, like this:

Q: Is the Application ID the same as the application package name?

A: If you haven’t set the Application ID in build.gradle, it defaults to the application package name. If you configure it as shown above, the Application ID will match the name in build.gradle and can differ from the application package name.