Define APM, then list and define its levels- APM is Advanced Power Managment.
Full On: Evertying in the system is running at full power. There is no power managment.
Enabled: CPU and RAM are running at full power. Power managment is enabled. An unused device may or may not be shut down.
Standby: CPU is stopped. RAM still stores all programs. All preipherals are shut down, although configuration options are still stored. (In other words, to get back to "Enabled" you won't have to reinitialize the devices)
Suspend/Hybernation: Everything in the PC is shut down or at its lowest power-consumption. Many systems use Hibernation, which is a special kind of Suspend where the programms in the RAM are written to a hard drive. Upon a "wake up" event, the system is reinitialized, and the data is read from the drive to return the system to "Enabled"