What is the difference between a background service and a background service in Android?

The difference between a regular background service and a restricted (restricted) background service appeared with Android 8.0 (API 26).

Regular background service:

• Can run indefinitely in the background.
• The system can terminate it when resources are scarce, but it can be restarted if START_STICKY was returned in onStartCommand().
• Does not require visible notifications (though this is not best UX practice).
• Can consume significant battery and CPU resources.

Restricted background service (with restrictions):

• A service started in the background without visible activities or other "whitelists" (privileged conditions) faces resource usage restrictions.
• Main restrictions include:
  • Background execution limit: The service can be stopped by the system shortly (usually a few minutes) after the app goes to background.
  • Prohibition on starting new background services: Background apps cannot start new background services with startService(). Instead, JobScheduler or WorkManager should be used.
  • Broadcast limitations: Implicit broadcasts in the manifest are ignored. Apps must register broadcast receivers explicitly or use JobScheduler/WorkManager.
• The goal of these restrictions is to improve battery life and device performance by limiting inefficient background resource usage.

How a service becomes unbounded (active in the eyes of the system):

• The app is in the foreground (user actively interacts with it).
• The app starts a visible service (foreground service), which shows a persistent notification.
• The app performs certain tasks (e.g., broadcast message processing, JobScheduler tasks) that temporarily lift it from a fully background state.

Main difference: From Android 8.0 and above, a service running in the background without user interaction or a visible service will be restricted by the system in terms of resource access and long-term operation. The regular "background service" before Android 8.0 could run without such restrictions.