
It then shuts down the computer completely - but leaves a note on the hard drive to remind it, when it restarts, to load the state information and continue what it was doing before. Hibernate stores information about what the computer was doing onto the hard drive. To switch your computer back on, all that has to be done is a "wake" signal gets sent to the processor, then it carries on doing what it was doing before, so it can restart very quickly. But because the processor is doing nothing except remembering its state, it uses very low power. Sleep keeps the processor powered, so that it remembers what it's doing.
