What do individual components or parts of the system refer to?.

In Android, individual components or parts of the system refer to various elements of the application or platform, such as Activity, Service, BroadcastReceiver, and ContentProvider. These components interact with each other through Intent — an object that describes the action to be performed and the data to be transferred.

For example, an Activity can start another Activity by sending an Intent with the necessary information. Thus, links between components are links through Intent, which allow the system and applications to interact and exchange data.