Hibernation is a feature of Windows operating system. When you hibernate computer, content of RAM is saved to hard disk before power off. When you turn on your computer next time, system will be restored to the state before powering off. This means that all programs will continue executing as nothing happened. Restoring from hibernation i usually faster than normal boot. Hibernation feature takes the same amount of space on hard drive as you have RAM installed.
Follow these steps to enable hibernation: