All Android application continue running and in memory until the system needs resources for other application. A main four components of Android Application use the application manifest file AndroidManifest.xml describes each component.
Activity processes have application components the user is interacting with. Its represents the presentation layer of an Android application. Its presents screen in your application.
Android offers the Service class to create application components that handle long-lived aperation and include functionality that doesn't require a user interface.
Services are started, stopped and controlled from other application components, including Activities, Broadcast Receivers, and other Services.
Intent are used as a message-passing mechanism that both within your application and between application
Broadcast Intents are used to notify application of system or application events, extending the event-driven programming model between applications.
Within your application, construct the intent you want to broadcast and call send Broadcast to send it .
Content Providers provide a interface for publishing and the content:// schema. Content Providers can be shared between applications, queried for results, have their existing record deleted or updated, and record added.