SystemUI

SystemUI is a core component of the Android operating system that provides the system user interface. It is delivered as a system application, typically named com.android.systemui, and runs in the system user space to render and manage UI elements that are not part of individual applications.

Its primary responsibilities include the status bar, notification shade, quick settings, the navigation bar or gesture navigation, and the recent apps interface. It also handles lock screen interactions and coordinates global UI chrome such as the clock, battery, and signal indicators that appear across the top of the screen.

In terms of architecture, SystemUI communicates with core system services and managers such as the WindowManager, NotificationManager, PowerManager, Keyguard, and ActivityTaskManager. It renders system UI, applies theme and animation, handles user input gestures, and updates UI elements in response to system events.

Development and distribution: SystemUI is part of the Android Open Source Project. The reference implementation resides in the AOSP packages/SystemUI directory and is updated with Android releases. Device manufacturers may customize SystemUI to create their own skins and behavior while preserving the core framework.

Security and stability: Because SystemUI operates with elevated privileges to control global UI components, it is designed for robustness and isolation from third-party apps. Failures in SystemUI can affect the entire user experience, and devices provide mechanisms to restart it without a full reboot when problems occur.

Overall, SystemUI forms the visible layer of Android on most devices, coordinating status indicators, notifications, and navigation to deliver a consistent user experience across apps.