The MacBook Pro features a backlight for the keyboard that helps illuminate the keys in low light conditions. By default, the keyboard lighting is adjusted automatically by an ambient light sensor that's located beside the FaceTime camera. However, you can turn off the option to automatically illuminate the keyboard and manually control the brightness on your own.

Adjusting the Keyboard's Brightness

Turn off automatic keyboard illumination by going to "System Preferences," and then clicking on "Keyboard." Uncheck the "Automatically illuminate keyboard in low light" option, and then control the keyboard backlight brightness yourself by pressing the "F5" key to lower and the "F6" key to raise the level. Note that even if the automatic brightness setting is turned on, you can still adjust brightness levels using those keys, but only when the ambient light sensor detects low enough light to turn the keyboard backlight on.