Doze mode is a power-saving feature in Android devices that helps extend battery life by reducing background activity when the device is not in use. When the screen is off and the device is stationary, Doze mode limits app updates, syncs, and other processes, allowing the battery to conserve energy. This mode activates automatically after a period of inactivity, ensuring that essential notifications still come through while minimizing resource usage. Users can customize which apps are allowed to run in the background during Doze mode, providing a balance between battery efficiency and app functionality.