An application ID (App ID) is an unique ID that identifies your iOS application within Apple’s application services. This ID enables you to use in-app purchasing, push notifications, game center, and so on. You must have a registered App ID before you create a provisioning profile.
You can create two types of App IDs.
Explicit App ID: Use this App ID to incorporate Apple application services in your application and create a unique provisioning profile for your application. You cannot use an explicit App ID across multiple applications and provisioning profiles. To create an explicit App ID, you need to specify a unique bundle identifier. A bundle ID identifies an application. A bundle ID is used during the development process to provision devices and also used by the operating system when the application is distributed to customers. For example, services like Game Center and In-App Purchase use a bundle ID to identify your application.
Wildcard App ID: Use this App ID if you want to use a single App ID with a single provisioning profile across multiple applications. However, if you use this App ID, you cannot incorporate Push Notifications, In-App Purchase, and Game Center in your applications.