Hibernation allows you to dump the contents of your physical memory i.e. RAM to a file (hiberfil.sys) on the Hard Disk and go into a no-power mode.
Next time the computer starts, it will load the system state image from Hard Disk into the RAM and resume in the exact state that you left it in.. That was technical jargon, now let me explain it in layman's terms. "Hibernation" simply means saving the current state of your computer before shutting it down, so that it starts up in the same state i.e. with all your open windows and programs. The main advantages of hibernating your PC are
- You don't have to launch all your programs every time you start up your PC (you can have your web browser or documents open).
- In Hibernation mode Windows XP boots up really fast. The start up time is reduce to almost one-fourth.
So here is how you actually hibernate your Windows XP PC. Go to "Control Panel", open up "Power Options". Go to "Hibernate" tab and check the "Enable hibernation" option. Now hibernation is enabled. Now go to "Advanced" tab and select "hibernate" under "When I press the Power button on my computer" or "When I press the Sleep button on my computer". Now the computer will go into hibernation when you press the Power or Sleep button, depending on what you selected in the Control Panel. Next time it will start up from an image of system state at lightning fast speed, in the exact state that it was shut down!! Enjoy.
Note: Don't leave too many programs open while hibernating your PC. Otherwise its start up time will increase proportionally, as the amount of RAM increases when more more programs are running and it will take longer to write to disk and read as well when starting up.