You might also see another check box displayed: Help improve battery by optimizing the content shown and brightness. Even if you use it, you can still move the Brightness slider to fine-tune the brightness level for a built-in display. This automatic setting helps make sure your screen is readable wherever you go.
Select Brightness, look for the Change brightness automatically when lighting changes check box, and then select it to use this feature. To find out if your PC supports this, select Settings > System > Display. Some PCs can let Windows automatically adjust screen brightness based on the current lighting conditions. (If the slider isn't there, see the Notes section below.) Select the Network icon on the right side of the taskbar, and then move the Brightness slider to adjust the brightness.
