Shadow Copy (also called Volume Snapshot Service or VSS) is a feature in recent versions of http://www.answers.com/topic/microsoft-windows that allows taking manual or automatic backup copies or...
You can change a file back to its previous version or just look at it in a previous version.
They are save in the System Volume Information folder on the volume that you have enabled Volume Shadow Copy on.
a desire to do dark unmentionable thing to all of humanity
From the school you graduated...ask the Registrar's office.