A bundle ID precisely identifies a single app. A bundle ID is used during the development process to provision devices and by the operating system when the app is distributed to customers. For example, Game Center and In-App Purchase use a bundle ID to identify your app when using these app services. The preferences system uses this string to identify the app for which a given preference applies. Similarly, Launch Services uses the bundle ID to locate an app capable of opening a particular file, using the first app it finds with the given identifier. The bundle ID is also used to validate an app’s signature.
The bundle ID string must be a uniform type identifier (UTI) that contains only alphanumeric characters (A-Z,a-z,0-9), hyphen (-), and period (.). The string should be in reverse-DNS format. For example, if your company’s domain is Acme.com and you create an app named Hello, you could assign the string com.Acme.Hello as your app’s bundle ID.