Why is Fragment not considered part of the main Android components?

A Fragment in Android is not considered a core component of an application because it cannot exist independently — it must always be embedded within an Activity. The main components of Android are those that can operate independently and are declared in the application's manifest (Activity, Service, BroadcastReceiver, ContentProvider).

A Fragment is used to create a modular and reusable UI within an Activity, making it easier to adapt the interface for different screen sizes and orientations. However, a Fragment itself does not have a lifecycle independent of the Activity and cannot be launched on its own.

Therefore, a Fragment is an auxiliary component that extends the capabilities of an Activity, rather than a standalone core component of an application.