Standby is the action where the CPU is held in a low power state but no data is saved to RAM or hard disk. It normally takes a a split second to standby and resume. You cannot remove the battery when on laptop power or work will be lost.
Suspend is the action where the computer freezes all activity, and copies working data to RAM. It then turns off the screen, and goes into a low-power mode. It normally takes a few seconds to suspend and a few seconds to resume. You cannot remove the battery when on laptop power or work will be lost.
Hibernate is the action where the computer freezes all activity and copies data to disk, turns off the screen and powers down. This takes over one minute for me to swap my ram to disk, and nearly 40 seconds to thaw.
Sleep is a composite generic term which means all of the above states.
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Sharique uddin Ahmed Farooqui
Developer
I too. I've kpowersave. But normally in the blue and red "Log out" applet we just have the choice between shutdown and logout, but no suspendRAM/ ROM or something like this!