Suspend and resume provides a way for the computer to shut off or lose power and then, once power returns, restore the system to the state before the power loss. The Suspend feature saves the computer's RAM contents on the hard disk before turning off the power. The difference between the Suspend state and normal power off is the presence of the saved RAM contents, along with some other hardware information, on the hard disk.
IMPORTANT
Drivers are required to save whatever is necessary to restore state after a loss of power.
The Energy Saver control panel has a checkbox that lets the user specify whether or not to save memory before the system goes into Sleep mode. The default is yes.
When the user presses the power key, the computer starts up and automatically reloads the RAM contents from the hard disk. The computer goes through a process similar to a normal boot, but it does not display the startup screen or the extension icons. It restores the prior state and resumes execution of whatever application was active at the time the system shut down.