+Screen brightness can be adjusted in various ways.
+The available methods depend heavily on the hardware, so it's recommended to try the features described in the following sections.
+
+[[backlight]]
+=== backlight
+
+The man:backlight[8] utility is included with the operating system.
+It is used to set the brightness of devices located under [.filename]#/dev/backlight/#.
+
+The command `backlight -f _device_ _value_` sets the brightness of _device_ to _value_, where _value_ is an integer between 0 (dim) and 100 (bright).
+If no device is specified, the default device [.filename]#/dev/backlight/backlight0# is considered.
+
+Example for setting the brightness of the default device to 50%:
+
+[source,shell]
+....
+% backlight 50
+....
+
+[NOTE]
+====
+Unless the user belongs to the "video" group, the command needs to run as root.
+====
+
+[[acpi_video]]
+=== acpi_video
+
+The man:acpi_video[4] driver, included with the operating system, uses the ACPI Video Extensions to control display switching and backlight brightness.
+To load the kernel module, run:
+
+[source,shell]
+....
+# kldload acpi_video
+....
+
+Brightness settings can be configured using extref:{handbook}config/#configtuning-sysctl[sysctl(8)].
+The following parameters are available:
+
+- hw.acpi.video._device_.levels: List of supported brightness levels.
+- hw.acpi.video._device_.brightness: Current brightness level of the device.
+
+_device_ is a possible display device.
+Example to set the brightness to 50% for the lcd0 device: