Hibernate is an in-built feature in the Windows 7 operating system, which enables the operating system to control power to your computer and peripheral devices. This is a standard technology known as the Advanced Configuration and Power Interface (ACPI).
Removal of traditional shutdown, restart or hibernate option has puzzled a lot to Windows 8 users. And understanding the concern, Microsoft has added these power options in "Win+X" Menu under Windows 8.1, which we also call "Quick Access Menu."