Which thread is used to run a service in the system?

In Android, services by default run on the main (UI) thread of the application. This means that if long or blocking operations are performed in a service, it can lead to UI slowdown and poor user experience.

To avoid this, it is recommended to run heavy tasks in a separate thread within the service, for example, using IntentService (which runs in a separate thread) or by creating new threads or using HandlerThread.

Thus, the service itself runs on the main thread, but for long operations, separate threads should be created.