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The essential building blocks of an Android application are called components.

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Each type serves a distinct purpose and has a distinct lifecycle that defines how the component is created

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and destroyed.

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The communication between these components is done using messages called intense.

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It is important to note that all these components need to be listed in the Android manifest dot sml

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file.

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These four components are listed on the screen.

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An activity is the entry point for interacting with the user.

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It represents a single screen with a user interface.

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Each activity is independent from others services.

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A service is a general purpose entry point for keeping an app running in the background for all kinds

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of reasons.

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It is a component that trons in the background to perform long running operations or to perform work

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for remote processes.

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A service does not provide a user interface.

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Broadcast's receivers, a broadcast receiver is a component that enables the system to deliver events

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to the application outside of a regular user flow, allowing the app to respond to system wide broadcast

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announcements because broadcast receivers are another well-defined entry into the app.

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The system can deliver broadcasts even to apps that aren't currently running, although broadcast receivers

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don't display a user interface.

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They may create a status by notification to alert the user when a broadcast event occurs.

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Content Providers, a content provider, manages a shared set of ABS data that you can store in the

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file system in a Ascui Alight database on the Web or on any other persistance storage location that

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your app can access through the content provider.

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Other apps can query or modify that data if the content provider allows it.

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For example, the Android system provides a content provider that manages the user's contact information

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as such.

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Any app, with the proper permission, can query the content provider to read and write information

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about a particular person.