Although each flashlight application is different, you can activate most of them by selecting the application's icon from the device's installed applications list and then pressing a simulated power button or switch within the application. Additionally, you can activate some flashlight applications from a home screen shortcut or widget.
Flashlight applications often have interfaces that simulate real flashlights, with a power button or switch, brightness settings and mode toggles. Flashlight applications that use the device's main screen as the point of illumination rather than an LED may have no user interface at all. These types of flashlight applications are always on and turn off only when the user closes the application.