What is hibernation?

[Demon]

On a PC, what exactly is this? Is it worth disabling? It uses an awful lot of memory on my machine.

 

[Redline]

In Hibernation mode your system goes to a complete shutdown. Just before your system goes to Hibernation mode, the current state of your operating system is saved to your hard drive and then shuts down. If you are the type of user that likes to shutdown your system but hates the long cold boot up, this is the best way to go. Waking up from Hibernation mode is faster than cold booting your system.