Hibernation is a useful feature of modern computers/operating systems, which allows users to turn off the computer for a while and later resume their session from that point, eliminating the need to save all work before shutting down. It is similar to the "Sleep" or "Suspend" option, but the computer won't keep on drawing power when hibernated, because all the information in the memory is written to the disk and therefore there is no need to feed power to the memory. I use this option to power down my system unless I perform some operation that specifically requires shut down instead of hibernation.