What Components Makes An Android Apps?

Activity:-

Activities are one of the fundamental building blocks of apps on the Android platform. They serve as the entry point for a user's interaction with an app, and are also central to how a user navigates within an app (as with the Back button) or between apps (as with the Recents button). In terms of desktop development, an Activity is
equivalent to a Form.

Services:-

The invisible workers of your application. Service components run invisibly, updating
your data sources and visible Activities and triggering Notifi cations. A Service is an application component that can perform long-running operations in the background, and it does not provide a user interface. Another application component can start a service, and it continues to run in the background even if the user switches to another application.

There are three types of service:-
1. Foreground
2. Background
3. Bound

Content Providers:-

A shareable data store. Content Providers are used to manage and share
application databases. Content Providers are the preferred way of sharing data across application
boundaries. This means that you can confi gure your own Content Providers to permit access
from other applications and use Content Providers exposed by others to access their stored data.
Android devices include several native Content Providers that expose useful databases like contact
information.

Intents:-

 A simple message-passing framework. Using Intents, you can broadcast messages system-wide
or to a target Activity or Service, stating your intention to have an action performed.
The system will then determine the target(s) that will perform any actions as appropriate.

Broadcast Receivers:-

Intent broadcast consumers. By creating and registering a Broadcast
Receiver, your application can listen for broadcast Intents that match specific filter criteria.
Broadcast Receivers will automatically start your application to respond to an incoming Intent,
making them ideal for event-driven applications.

Notifications:-

A user notifi cation framework. Notifications let you signal users without stealing
focus or interrupting their current Activities. They’re the preferred technique for getting
a user’s attention from within a Service or Broadcast Receiver. For example, when a device
receives a text message or an incoming call, it alerts you by flashing lights, making sounds, displaying icons, or showing dialog messages.