According to
this article;
Also known as "smart battery", hibernate is a utility designed to keep the desktop settings and program settings currently being used or worked on when laptop computer looses its power. When the computer is turned back on the hibernate feature restores your programs and settings exactly as you left them when the computer was turned off.
Note the text converted to Italic.
If this is true, then why do people make use of it? No wonder there are so many Hibernation issues as of late when it is only meant as an emergency feature!