Advanced Power Management definition hardware
(APM) A feature of some displays, usually but not always, on laptop computers, which turns off power to the display after a preset period of inactivity to conserve electrical power. Monitors with this capability are usually refered to as "green monitors", meaning environmentally friendly.
Not to be confused with a screen blanker
which is software
that causes the display to go black (by setting every pixel
to black) to prevent burn-in